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  • 101
    Electronic Resource
    Electronic Resource
    Polyine, 9. Umsetzungen von Butadiindiaminen und eines Butadiinamins mit Arylisocyanaten (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 221-226 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polyynes, 9. - Reactions of Butadiynediamines and of One Butadiynamine with Aryl IsocyanatesThe butadiynamine 6 and the butadiynediamines 5a-c react with the aryl isocyanates 7a-c and 8 by cyclization to give the 2-quinolone derivatives 10 and 11. The representatives of 10 and 11 bearing an aminoethinyl moiety formed formed from diynamines 5 cyclize on heating in ethanol to furnish the furo[2,3-b]quinolines 12 and 13, respectively. The reaction sequence is confirmed by an X-ray structural analysis (12c).
    Notes: Das Butadiinamin 6 und die Butadiindiamine 5a-c reagieren mit den Arylisocyanaten 7a-c und 8 unter Cyclisierung zu den 2-Chinolon-Derivaten 10 und 11. Die unter Verwendung der Diindiamine 5 hergestellten Vertreter 10 und 11 mit Aminoethinyl-Teil cyclisieren beim Erhitzen in Ethanol zu den Furo[2,3-b]chinolinen 12 bzw. 13. Die Reaktionsfolge wird durch eine Kristallstrukturanalyse (12c) gesichert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870311
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  • 102
    Electronic Resource
    Electronic Resource
    Chemie und Stereochemie der Iridoide, VIII. Über die Oxidation der Enolether-Funktion von Catalpol-Derivaten zum Lacton (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 227-230 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry and Stereochemistry of Iridoids, VIII. - Oxidation of the Enol-Ether Function of Catalpol Derivatives to the LactoneOxidation of 2′,3′,4′,6,6′,10-hexaacetylcatalpol (1a), 2′,3′,4′,6-tetraacetyl-6′,10-bis(triphenylmethyl)catalpol (1b), and 2′,3′,4′,6′,10-pentaacetyl-6-(acetylvanilloyl)catalpol (1c) by N-bromosuccinimide/dimethyl sulfoxide is described. A mixture of the two possible diastereomeric α-bromolactones 2 is obtained in each case. This mixture can be reduced as crude product in dry tetrahydrofuran by treatment with zinc/acetic acid to yield more than 70% of the halogen-free lactones 3. The mechanism of the reaction is discussed.
    Notes: Die Oxidation von 2′,3′,4′,6,6′,10-Hexaacetylcatalpol (1a), 2′,3′,4′,6-Tetraacetyl-6′,10-bis(triphenylmethyl)catalpol (1b) und 2′,3′,4′,6′,10-Pentaacetyl-6-(acetylvanilloyl)catalpol (1c) mit N-Bromsuccinimid/Dimethylsulfoxid wird beschrieben. Das jeweils entstehende Diastereomerengemisch der zwei möglichen α-Bromlactone 2 läßt sich als Rohprodukt mit Zink/Eisessig in wasserfreiem Tetrahydrofuran zu den halogenfreien Lactonen 3 reduzieren, wobei die Gesamtausbeuten höher als 70% sind. Der Reaktionsmechanismus wird diskutiert.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870312
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  • 103
    Electronic Resource
    Electronic Resource
    Zur Kenntnis zweier nichtnatürlicher Pteridinpigmente (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 259-261 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on Two Naturally Not Occurring Pteridine PigmentsThe syntheses of the artefacts 2 and 6, which result from workup of biological material containing xanthopterin (1) and isoxanthopterin (5), are described.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870317
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  • 104
    Electronic Resource
    Electronic Resource
    Ein einfaches Verfahren zur vollständigen Methylierung der α-Positionen einiger Ketone (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 263-264 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Convenient Procedure for Complete Methylation of the α-Positions of Some Ketones2,2,6,6-Tetramethylcyclohexanone (2a), Pivalophenone (4a), and other complete methylated ketones can be prepared by a simple procedure. Therefore the ketone was treated with methyl iodide and powdered KOH in the presence of catalytical amounts of [18]crown-6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870318
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  • 105
    Electronic Resource
    Electronic Resource
    Synthese furanoider Epithio-MDP -analoger Derivate als potentielle Immunostimulantien (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 283-288 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Furanoid Epithio-MDP Analogs as Potentially Immunostimulating AgentsSyntheses of gluco- as well as ido-5,6-epithio analogs of N-acetylmuramyl dipeptide (MDP), starting from a common educt, are described. These derivatives are designed as sulfur analogs eventually being more reactive in metabolism than the products known up to now. All products are characterized by their NMR spectra (1H and 13C).
    Notes: Synthesen von gluco-sowie ido-5,6-Episulfidanalogen von N-Acetylmuramyl-dipeptid (MDP), in welchen der Schwefel im Kohlenhydratteil dem metabolisierenden System in reaktiverer Form angeboten werden kann, werden beschrieben. Dabei werden aus einem gemeinsamen Edukt beide Diastereomere zugänglich gemacht. Alle Produkte wurden NMR-spektroskopisch (1H und 13C) eindeutig charakterisiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870323
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  • 106
    Electronic Resource
    Electronic Resource
    Insect Growth Regulators, 20. Synthesis of Cyclic Analogues of Juvenile Hormone-III (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 169-173 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Insektenwachstumsregulatoren, 20. - Synthese cyclischer Analoga von Juvenilhormon-IIIDas cyclische JH-III-Analogon rac-14b und sein 2Z-Isomer rac-14a wurden durch eine Mehrstufensynthese ausgehend von rac-α-Terpineol erhalten. Die Wadsworth-Emmons-Reaktion wurde zur Bildung der Kohlenstoffkette und zur Einführung der Esterfunktion (Ester 8a, b und 13a, b) verwandt. Die morphogenetischen Aktivitäten der cyclischen Juvenoide wurden mit denen für acyclische Analoga verglichen.
    Notes: The cyclic analogue rac-14b of JH-III and its 2Z isomer rac-14a were obtained by a multi-step synthesis starting from rac-α-terpineol. The Wadsworth-Emmons reaction was applied to the formation of the carbon chain and to the introduction of the ester function (esters 8a, b and 13a, b). Morphogenetic activities of the cyclic juvenoids were compared with those observed for their acyclic analogues.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870302
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  • 107
    Electronic Resource
    Electronic Resource
    Neue Pyridothiazine und Pyrimidothiazine aus 1-Methyl-1λ4,4-thiazin-1-oxiden und 1,3-Biselektrophilen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 551-553 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Pyridothiazines and Pyrimidothiazines from 1-Methyl-1λ4,4-thiazine 1-Oxides and 1,3-BiselectrophilesThe aminothiazines 1a-d are easily acylated by 2-(1-methoxyethylidene)malononitrile (2) and ethyl N-cyanoacetimidate (5a). The intermediates 3a-d and 6a, b are converted into the bicyclic products 4a-d and 7a, b with sodium hydride. The N-cyanoimidates 5b-g react with selected thiazines 1 and sodium hydride to give the pyrimidothiazines 7c-i immediately.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870376
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  • 108
    Electronic Resource
    Electronic Resource
    Synthesis of the Methyl Ester of (2R,4R,6R,8R)-2,4,6,8-Tetramethylundecanoic Acid, an Acid Component of the Preen-Gland Wax of the Graylag Goose, Anser anser (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 555-556 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methyl ester 1a of (2R,4R,6R,8R)-2,4,6,8-tetramethylundecanoic acid found in the feather wax of the graylag goose was synthesized from optically pure lardolure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870377
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  • 109
    Electronic Resource
    Electronic Resource
    Strukturaufklärung von C10H14-Dehydroterpenen durch Reaktionsgaschromatographie Nachweis neuer Terpenkomponenten in etherischen Ölen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 557-559 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structure Elucidation of C10H14-Dehydroterpenes by Reaction Gas-Chromatography. - Identification of New Terpene Constituents in Essential OilsAlumina-catalyzed dehydration of C10H16O-monoterpene alcohols and elimination of acetic acid from C10H15OCOCH3-monoterpene acetates were carried out in the injection port of a gas chromatograph. The C10H14-monoterpene hydrocarbons formed were analyzed by gas chromatography and mass spectrometry. By means of this reaction gas chromatographic technique, verbenene (7) and 1,5,8-p-menthatriene (13) were identified unequivocally, for the first time, as constituents of essential oils.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870378
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  • 110
    Electronic Resource
    Electronic Resource
    Verzweigte und kettenverlängerte Zucker, XXXI. Synthese des Sauerstoffanalogons der Desferriform von δ1-Albomycin (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 565-575 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Branched and Chain-Extended Sugars, XXXI. - Synthesis of the Deferri Form of the Oxygen Analogue of δ1-AlbomycinThe oxygen analogue of the deferri form of δ1-albomycin has been synthesized. Reaction of the xylo-dialdehyde 2 with the anion of the lithium salt 3 of N,N-bis(trimethylsilyl)glycine trimethylsilyl ester leads to the chain-extended sugar. In good stereochemical selectivity the desired 6-amino-6-desoxy-L-ido-hepturonic acid is isolated as derivative 8. After transformation of 8 into the 1-acetate 23 the nucleoside 26 is obtained by a modification of the Hilbert-Johnson reaction using the uracil derivative 24. N-Methylation of 26 gives 28 in good yield. The serine derivative 31 reacts with the deblocked amino compound 30 to yield the peptide nucleoside 32. The tripeptide 36, which contains three units of N5-acetyl-N5-hydroxy-L-ornithine, is successfully linked to the partial deblocked compound 34 via the mixed carbonic anhydride method. Final hydrogenation of 37 gives the free deferri form of the oxygen analogue 38.
    Notes: Es wird das Sauerstoffanalogon der Desferriform des δ1-Albomycins synthetisiert. Zum Aufbau des Zuckerteils wird die xylo-Dialdopentofuranose 2 mit dem Anion des Lithiumsalzes 3 von N,N-Bis(trimethylsilyl)glycin-trimethylsilylester umgesetzt. Die gewünschte 6-Amino-6-desoxy-L-glycero-L-ido- heptofuranuronsäure wird mit guter Stereoselektivität gebildet und nach Derivatisierung als Verbindung 8 isoliert. Nach Überführung von 8 in das 1-Acetat 23 ist mit Hilfe der modifizierten Hilbert-Johnson-Methode unter Verwendung des Uracil-Derivates 24 das Nucleosid 26 darstellbar, das zu 28 N-methyliert werden kann. Nach dem Aktivesterverfahren ist nach Freisetzung der Aminogruppe zu 30 eine Anknüpfung des Serin-Derivates 31 zum Peptid 32 möglich. Nach partieller Entblockierung zu 34 gelingt mit der Methode der gemischten Anhydride die Anknüpfung des Tripeptids 36, welches aus drei Einheiten von N5-Acetyl-N5-hydroxy-L-ornithin besteht. Durch Hydrogenolyse ist aus 37 die freie Desferriform des Sauerstoffanalogons 38 erhältlich.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870702
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  • 111
    Electronic Resource
    Electronic Resource
    Chemie der Nitrosamine, V. Synthesen von α-funktionellen N-Nitrosodialkylaminen: Dithioester und Thioether (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 583-588 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Nitrosamines, V. - Syntheses of α-Functional N-Nitrosodialkylamines: Thioethers and DithiocarbamatesThe in vivo reaction products of electrophilic compounds with glutathione are excreted as S-alkyl-N-acetylcysteins (mercapturates) after enzymatic degradation. The results clearly show that mercapturates as 1-substituted N-nitrosodialkylamines 11 are chemically stable enough to be isolated and characterized. The reactions of 1-chloro-N-nitrosodialkylamines 5 with 3,4-dichlorothiophenol, ethanethiol, and N,N-diethyldithiocarbamate illustrate the high tendency of formation of 1-thiosubstituted nitrosamines.
    Notes: S-Alkyl-N-acetylcysteine (Mercapturate) werden als enzymatische Abbauprodukte der Reaktion von Glutathion mit elektrophilen Verbindungen im Organismus ausgeschieden. Es wird gezeigt, daß Mercapturate als 1-substituierte N-Nitroso-Verbindungen 11 synthetisch zugänglich und stabil sind. Durch die Umsetzungen von 1-Chlor-N-nitrosodialkylaminen 5 mit weiteren Schwefelnucleophilen wie 3,4-Dichlorthiophenol, Ethanthiol und N,N-Diethyldithiocarbamat läßt sich die große Bereitschaft zur Bildung von 1-thiosubstituierten Nitrosaminen aufzeigen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870704
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  • 112
    Electronic Resource
    Electronic Resource
    6-(3-Carbamoylbicyclo[2.2.1]hept-2-yl)hexansäuren, eine neue Klasse von TxA2-Antagonisten (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 607-615 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 6-(3-Carbamoylbicyclo[2.2.1]hept-2-yl)hexanoic Acids, a New Class of TxA2 AntagonistsThe synthesis of prostanoids 20-27, 40a, b, and 45a, b starting from the educts 1a, b, and 31 is described. Configurational changes concerning to the positions 2 and 3 of the bicyclic system were proofed by 13C-NMR spectroscopy and were also used for the preparation of the four exo/endo derivatives. 25 and 26 are potent TxA2 antagonists.
    Notes: Die Synthese der Prostanoide 20-27, 40a, b und 45a, b aus den Edukten 1a, b und 31 wird beschrieben. Die bezüglich der 2- und 3-Stellung am Bicyclus beobachteten Konfigurationsänderungen wurden durch 13C-NMR-Spektroskopie geklärt und auch für die Herstellung der vier exo/endo-Derivate genutzt. 25 und 26 erwiesen sich als stark wirksame TxA2-Antagonisten.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870707
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  • 113
    Electronic Resource
    Electronic Resource
    Synthese von 1α-Hydroperoxy-Zuckerderivaten (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 637-638 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 1α-Hydroperoxy Sugar DerivativesThe title compounds 4 and 5 can be prepared from acetylated glycals with H2O2 under acid catalysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870712
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  • 114
    Electronic Resource
    Electronic Resource
    Synthese von Isochino[1,2-a][2]benzazepinen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 639-641 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Isoquino[1,2-a][2]benzazepinesA simple method for the synthesis of 12-alkoxyisoquino[1,2-a]-[2]benzazepines 6 in good yields starting from 3-(3-alkoxyphenyl)propylamines 1 and 1-isochromanone (2) is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870713
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  • 115
    Electronic Resource
    Electronic Resource
    Synthesen von Methyl-4-O-(β-D-curacosyl)-α-D-curamicosid, dem Glycosid der Disaccharideinheit E—F von Flambamycin und Isomeren (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 289-295 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Methyl 4-O-(β-D-Curacosyl)-α-D-curamicoside, the Glycoside of the Disaccharide Moiety E—F of Flambamycin and IsomersBy application of the tetraisopropyldisiloxy function a five-step synthesis of the selectively protected 2,6-di-O-methylmannopyranoside 5a is achieved. Additionally several steps are used to transfer the galactopyranoside 7 into the α-bromide of 4-O-methylfucose 15. By silver triflate-mediated condensation the disaccharide 16, a derivative of the disaccharide moiety E—F of flambamycin, is obtained. For comparison, also 6a was glycosylated with 15 to yield the regioisomer 17. Another route made the fucosyl bromide 25 accessible. 25 could be condensed with 5a following the in-situ anomerization procedure to give the α,1→4-linked isomer 26.
    Notes: Durch Einsatz der Tetraisopropyldisiloxyfunktion wird in einer fünfstufigen Synthese die Darstellung des selektiv geschützten 2,6-Di-O-methylmannopyranosids 5a erreicht. Außerdem läßt sich aus dem Galactopyranosid 7 in mehreren Schritten das α-Bromid der 4-O-Methylfucose 15 herstellen. Die Silbertriflatkondensation ergibt glatt das Disaccharid 16, ein Derivat der E—F-Disaccharideinheit von Flambamycin. Zum Vergleich wurde aus 6a und 15 das Regioisomer 17 synthetisiert. Auf anderem Weg war das Fucosylbromid 25 zugänglich, das nach dem In-situ-Anomerisierungsverfahren mit 5a zum α,1→4-verknüpften Isomer 26 umgesetzt werden kann.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870324
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  • 116
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    Electronic Resource
    Metal Complexes with Tetrapyrrole Ligands, XLIV. Configuration and Conformation of the anti-5,15-Dialkyl-2,3,7,8,12,13,17,18-octaethyl-5H,15H-porphyrins (Decaalkylporphodimethenes) (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 305-309 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metallkomplexe mit Tetrapyrrol-Liganden, XLIV. - Konfiguration und Konformation der anti-5,15-Dialkyl-2,3,7,8,12,13,17,18-octaethyl-5H,15H-porphyrine (Decaalkylporphodimethene)Die Konfigurationen und Konformationen der 5,15-Dialkyloctaethylporphodimethene H2(OEPR2) mit R = Me, Et, iPr, tBu werden beschrieben. Die „normalen“ Verbindungen (1a-1d) haben die syn-axiale-(„aa“-)Konfiguration, die „anomalen“ Isomeren (2b-4b) die anti-Konfiguration an C5,15. Das beweist eine Kristallstrukturanalyse des anomalen quasiplanaren Diisopropyl-Derivats 3b (monoklin, P21/a). 1H-NMR-Analysen bestätigen diese Zuordnungen und liefern Details der Konformationen in Lösung. Heißer Eisessig isomerisiert 3b quantitativ zu 3a.
    Notes: The configurations and conformations of 5,15-dialkyloctaethylporphodimethenes H2(OEPR2) are described for R = Me, Et, iPr, tBu. The „normal“ compounds (1a to 1d) have the syn-axial („aa“) configuration, the „anomalous“ isomers (2b to 4b) the anti configuration at C5,15. This is proved by a crystal structure analysis of the anomalous quasiplanar diisopropyl derivative 3b (monoclinic, P21/a). 1H-NMR analyses corroborate these assignments and give details of the conformations in solution. By heating in glacial acetic acid, 3b is quantitatively isomerized to give 3a.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870326
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  • 117
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    Radikalreaktionen an N-Heterocyclen, VI. Reaktionen cyclischer 2,2-Diacyl-1-arylhydrazyle Eine neue N—N-Spaltungsreaktion (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 671-678 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Free Radical Reactions of N-Heterocyclic Compounds, VI. - Radical Reactions of Cyclic 2,2-Diacyl-1-arylhydrazyls. - A New N—N Bond Cleavage ReactionDiacylhydrazyl radicals 5 are generated from N-(phenylamino)-dicarboximides 1, 2a, b, 3a-f, and 4 by oxidation with different oxidants. The intermediates 5 react in two ways depending on the substituents in the anilino group. Dimerization of the hydrazyl radicals 5 to stable tetrazanes 8 is favoured by acceptor substituents in the Ar group. N—N bond dissoziation (α-decomposition) of the hydrazyl radicals 5 is favoured by donor substituents in the phenyl ring of the anilino group. The fragments of such reactions are imide radicals 22 and phenylnitrenes 23. The formation of these fragmentation products is proven by analysis of the reaction products. The formation of benzoxazole (25) (15% yield) is an evidence for an intramolecular insertion reaction of the o-methoxyphenylnitrene, generated by oxidation of 3e. The hydrazyl radicals 5 are also trapped by the stable free radical 2,4,6-tri-tert-butylphenoxyl (9). The thermal decomposition of the isolated radical adducts was studied.
    Notes: Die Diacylhydrazyl-Radikale 5 werden aus den N-(Phenylamino)dicarbonsäureimiden 1, 2a, b, 3a-f und 4 durch Oxidation mit verschiedenen Oxidantien erzeugt. Die Radikale 5 reagieren auf zwei Wegen: a) Dimerisation zu Tetrazanen 8, die durch Akzeptorsubstituenten im Anilinorest begünstigt wird; b) durch N—N-Bindungsspaltung, wobei Imid-Radikale 22 und Phenylnitrene 23 entstehen, bei donatorsubstituierten Anilinogruppen. Die Spaltprodukte werden als Folgeprodukte nachgewiesen, so Benzoxazol (25) (15%), das durch Oxidation von 3e über das intermediäre o-Methoxyphenylnitren gebildet wird. Die Hydrazyl-Radikale 5 konnten durch 2,4,6-Tri-tert-butylphenoxyl (9) abgefangen werden. Die Zersetzung der isolierten Abfangprodukte wurde untersucht.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870806
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    Reaktionen der Trialkylsilyl-trifluormethansulfonate, VI. Synthese von 2-heterosubstituierten O-Alkyl-O-(trimethylsilyl)ketenacetalen und 2-(Trimethylsilyl)carbonsäureestern (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 687-692 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Trialkylsilyl Trifluoromethanesulfonates, VI. - Synthesis of 2-Heterosubstituted O-Alkyl-O-(trimethylsilyl)ketene Acetals and 2-(Trimethylsilyl)carboxylatesOrganooxy- and (alkylthio)ethanoic acid esters 2 are silylated by trimethylsilyl triflate (1) in the presence of triethylamine to yield mixtures of ketene acetals 3 and 2-(trimethylsilyl)ethanoates 4. The product distributions 3/4 are governed by the ester groups and the substituents in α position. Cyclic derivatives of 2-hydroxycarboxylic acids 7,9 are silylated by 1/triethylamine to give the ketene acetals 8, 10. From N-protected glycine methyl esters 11, 12 the ketene acetals 13, 15 are obtained in the reaction with 1/triethylamine.
    Notes: Durch Silylierung von Organooxy- und (Alkylthio)essigestern 2 mit Trimethylsilyltriflat (1) in Gegenwart von Triethylamin erhält man Gemische aus Ketenacetalen 3 und 2-(Trimethylsilyl)essigestern 4. Die Produktverteilung 3/4 wird durch die Estergruppen sowie die α-Substituenten in den Estern 2 gesteuert. Cyclische Derivate der 2-Hydroxycarbonsäuren 7, 9 werden durch 1/Triethylamin in die Ketenacetale 8, 10 übergeführt. N-geschützte Glycin-methylester 11, 12 ergeben bei Umsetzung mit 1/Triethylamin die Ketenacetale 13, 15.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870809
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    Anomalously Coupled Nucleosides, II. Reaction of 3-[N6-(4-Chlorophenyl)-2-methyl-9-adenyl]-2,3-dideoxy-D-threo-pentopyranose with Alcohols and Anilines (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 705-708 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ungewöhnlich verknüpfte Nucleoside, II. - Reaktion von 3-[N6-(4-Chlorphenyl)-2-methyl-9-adenyl]-2,3-didesoxy-D-threo-pentopyranose mit Alkoholen und Anilinen3-[N6-(4-Chlorphenyl)-2-methyl-9-adenyl]-2,3-didesoxy-D-threo-pentopyranose (1) wurde in die Alkyl-3-[N6-(4-chlorphenyl)-2-methyl-9-adenyl]-2,3-didesoxy-D-threo-pentopyranoside 2 und die N-Aryl-3-[N6-(4-chlorphenyl)-2-methyl-9-adenyl]-2,3-didesoxy-D-threo-pentopyranosylamine 4 umgewandelt. Die Verbindungen 2 wurden als α/β-Anomeren-Gemische isoliert, bei verlängerten Reaktionszeiten wurden jedoch reine α-Anomere 3 erhalten.
    Notes: 3-[N6-(4-Chlorphenyl)-2-methyl-9-adenyl]-2,3-dideoxy-D-threo-pentopyranose (1) has been converted into the alkyl 3-[N6-(4-chlorophenyl)-2-methyl-9-adenyl]-2,3-dideoxy-D-threo-pentopyranosides 2 and into the N-aryl-3-[N6-(4-chlorophenyl)-2-methyl-9-adenyl]-2,3-dideoxy-D-threo-pentopyranosylamines 4. The compounds 2 were isolated as mixtures of α and β anomers whereas pure α anomers 3 could be obtained after prolonged reaction times.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870812
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    Syntheses of New Amino and Aziridino Sugar Derivatives of Potential Biochemical Interest (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 717-720 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesen neuer Amino- und Aziridino-Zuckerderivate von potentieller biochemischer RelevanzEffiziente Eintopfsynthesen für einige Amino- und Aziridinozucker mit potentieller biochemischer Relevanz werden beschrieben. Die Verbindungen werden durch eine C—N-Kupplungsreaktion von geschützten Zuckern und Estern der p-Aminobenzoesäure erhalten. Die freie Aminofunktion der letzteren wird durch eine SN2-Reaktion mit der Triflatgruppe der Zuckertriflate 1-3 zu einer neuen Klasse von Aminozuckerderivaten (4-8) umgesetzt. Die Reaktion von 4 und 5 mit Et2O—BF3 in Trimethylsilylazid liefert eine neue Klasse von Aziridinozuckern (9-10), welche durch eine Isomerisierung des α-Iminooxirans in ein α-Hydroxyepimin entsteht. Bei dieser Reaktion entstehen außerdem Benzyl-4-[4-(tert-butyloxycarbonyl)phenylamino]-4-deoxy-β-L-lyxopyranosid (11) und dessen α-D-Isomeres 12. Die Konformation der Verbindungen 4-11 wird durch 1H- und 13C-NMR-Spektroskopie bewiesen.
    Notes: Efficient one-pot syntheses of some amino and aziridino sugars of potential biochemical interest are developed by way of a C—N coupling reaction between suitably protected sugars and esters of p-aminobenzoic acid. The free amino function of the latter are utilized to cause SN2 displacement of the triflyl group in the sugar triflates 1-3 providing a new class of amino sugars (4-8). The reactions of 4 and 5 with Et2O—BF3 in trimethylsilyl azide afford a new type of aziridino sugars (9-10) through a novel isomerization of an α-iminooxirane into an α-hydroxyepimine. The reaction pathway also provides benzyl 4-[4-(tert-butyloxycarbonyl)phenylamino]-4-deoxy-β-L-lyxopyranoside (11) and its α-D-isomer 12. The conformation of compounds 4-11 are supported by 1H- and 13C-NMR spectroscopy.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870815
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    Methylen(hydroxyamino)dipeptidester. - Ein neues Peptidanalogon (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 729-730 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methylene(hydroxyamino)dipeptide Esters. - A New Peptide AnalogueThe preparation of methylene(hydroxyamino)dipeptide esters is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870819
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    Total Synthesis of (+)-Colletodiol from (S,S)-Tartrate and (R)-3-Hydroxybutanoate (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 733-744 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Totalsynthese von (+)-Colletodiol aus (S,S)-Weinsäure und (R)-3-HydroxybuttersäureDas Makrodiolid-Antibiotikum (+)-Colletodiol (7, Schema 1) wurde synthetisiert. Die (6R,11R,12R,14R)-Konfiguration wurde damit bewiesen. - Schlüsselprodukte (Schema 9 und 10) sind die zwei Hydroxycarbonsäuren 43 und 64, die in 20% Gesamtausbeute in 12 Stufen aus (S,S)-Weinsäure-dimethylester, respektive in 57% Gesamtausbeute in 6 Stufen aus (R)-3-Hydroxybuttersäure-methylester hergestellt wurden. Die zwei Hydroxysäuren wurden cyclisiert und ergaben, nach Abspaltung der Schutzgruppen, die Titelverbindung. - Auf dem Weg zu diesem Zielmolekül wurde eine große Anzahl von chiralen Synthesebausteinen hergestellt, viele von ihnen in mehreren stereoisomeren Formen.
    Notes: The macrodiolide antibiotic (+)-colletodiol (7, Scheme 1) was synthesised. The configuration was thus proven to be (6R,11R,12R,14R). - Key intermediates (Schemes 9 and 10) are the two hydoxy acids 43 and 64, which were prepared from dimethyl (S,S)-tartrate in 20% overall yield (12 steps) and from (R)-3-hydroxybutanoate in 57% overall yield (6 steps), respectively. The two hydroxy acids were cyclised to give, after deprotection, the title compound. - Our investigations led to the production of a large number of chiral building blocks, many of them in different stereoisomeric forms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870821
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    α,β-Unsaturated Nitriles in Organic Synthesis: A Novel Synthesis of Biaryls and Azabiaryls (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 477-479 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of (1-phenylethylidene)malononitrile (2) with cinnamonitrile derivatives 1a-e afforded the biaryl derivatives 6. The azabiaryls 8 and 10 were synthesized by the reaction of 2 with malononitrile and trichloroacetonitrile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870358
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    Synthetic microbial chemistry, XV. Synthesis of (2E,4R,5S,11R)-(-)-Cladospolide A, a Phytotoxic Macrolide from Cladosporium cladosporioides (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 863-869 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthetische Mikroben-Chemie, XV. - Synthese von (2E,4R,5S,11R)-(-)-Cladospolid A, eines phytotoxischen Makrolids aus Cladosporium cladosporioidesEs wird die Totalsynthese von Cladospolid A [(2E,4R,5S,11R)-4,5-Dihydroxy-2-dodecen-11-olid (1a)] in 16 Stufen aus (R)-3-Hydroxybutansäure-ethylester (2a) beschrieben.
    Notes: The total synthesis of cladospolide A [(2E,4R,5S,11R)-4,5-dihydroxy-2-dodecen-11-olide (1a)] was achieved in 16 steps from ethyl (R)-3-hydroxybutanoate (2a).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870841
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    Glycosidation, VII. Development of Selective Cytostatica for Cancer Therapy Synthesis of Acetal-β-glucosides from Cytotoxic Aldehydes (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 847-856 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosidierungen, VII. - Entwicklung selektiver Cytostatica für die Krebs-Therapie. - Synthese von Acetal-β-glucosiden von cytotoxischen AldehydenAldehyde sind stark cytotoxische Verbindungen, die jedoch normalerweise nicht für die Krebs-Therapie eingesetzt werden können, da sie schnell durch Bindung an Serumproteine desaktiviert werden. Es besteht jedoch die Möglichkeit, sie in Acetal-β-D-glucoside, eine nicht toxische Transportform, zu überführen, aus der sie durch enzymatische oder säurekatalysierte Hydrolyse freigesetzt werden können. Die acetylgeschützten Acetal-β-glucoside 4 werden in sehr guten Ausbeuten und hochselektiv durch Umsetzung von Trimethylsilyl-2,3,4,6-tetra-O-acetyl-β-D-glucopyranosid (1c) und einem Acetal 2 in Gegenwart katalytischer Mengen von Trimethylsilyl-trifluormethansulfonat (3) in Dichlormethan bei -70°C erhalten. Entacetylierung ergibt die freien Acetal-β-glucoside 5. In ähnlicher Weise kann Trimethylsilyl-2,3,4,6-tetra-O-benzyl-β-D-glucopyranosid (1e) zu den benzylgeschützten Acetal-β-glucosiden 6 umgesetzt werden. Die Bildung von 4 oder 6 gelingt auch durch Reaktion von 1c oder 1e mit Aldehyden 8 und Alkyltrimethylsilylethern 7 in Gegenwart von 3.
    Notes: Aldehydes are highly cytotoxic compounds, but they can normally not be used in cancer therapy because of fast binding to serum proteins. However, they could be transformed into acetal-β-glucosides 5, a nontoxic transport form, from which they can be freed by enzymatic or acid-catalyzed hydrolysis. The acetyl-protected acetal-β-glucosides 4 are obtained in excellent yield and highly selectively by reaction of trimethylsilyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside (1c) and an acetal 2 in the presence of catalytic amounts of trimethylsilyl trifluoromethanesulfonate (3) in dichloromethane at -70°C. Deacetylation gives the free acetal-β-glucosides 5. Similarly, trimethylsilyl 2,3,4,6-tetra-O-benzyl-β-glucopyranoside (1e) was used to afford the benzyl-protected acetal-β-glucosides 6. The formation of 4 or 6 can also be achieved by reaction of 1c or 1e with an aldehyde 8 and an alkyl trimethylsilyl ether 7 in the presence of 3.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870839
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    Stereoselective Syntheses of Alcohols, XXIV. Synthesis of 2,6-Dideoxy-L-hexoses (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 881-887 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereoselektive Synthesen von Alkoholen, XXIV. - Synthese von 2,6-Didesoxy-L-hexosenDurch Addition der Z- oder E-γ-Alkoxyallylboronsäureester 3 bzw. 6 an O-Benzylmilchsäurealdehyd erhielt man die 3,4,5-trihydroxylierten 1-Hexene mit arabino-, xylo-, ribo- und lyxo-Konfiguration. Die asymmetrische Induktion (arabino/xylo) bei der Addition von 3 lag bei 82:18, die bei der Addition von 6 bei 40:60 (ribo/lyxo). Die für Ausmaß und Richtung der asymmetrischen Induktion maßgeblichen Faktoren werden diskutiert. Sie weisen auf Übergangszustände vom Cornforth-Typ hin. Die einzelnen 3,4,5-Trihydroxy-1-hexene wurden in die 2,6-Didesoxy-L-hexosen mit arabino-, ribo-, und lyxo-Konfiguration übergeführt.
    Notes: Addition of the Z- and E-γ-alkoxyallylboronates 3 and 6 to O-benzyllactaldehyde led to various 3,4,5-trioxygenated 1-hexenes of arabino, xylo, ribo, and lyxo configuration. The extent of asymmetric induction amounted to 82:18 (arabino/xylo) in the addition of 3 and to 40:60 (ribo/lyxo) on addition of 6. The factors which determine the direction and extent of asymmetric induction are discussed, pointing to Cornforth-type conformations in the transition state. Individual members of the 3,4,5-trioxygenated hexenes were converted into 2,6-dideoxy-L-hexoses of arabino, ribo, and lyxo configuration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870843
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    Synthese von N,N′-Bipyrrolen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 893-894 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of N,N′-BipyrrolesA concise route to N,N′-bipyrroles 1 is described proceeding via intermediates 3, 4, and 5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870845
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    Darstellung und reaktivität von neuen bicyclischen β-Lactamverbindungen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 911-919 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Reactivity of Novel Bicyclic β-LactamsThe synthesis of the novel 8-oxo-1,3-diazabicyclo[4.2.0]oct-2-ene-2-carboxylates 1 is described as well as their enhanced reactivity under physiological conditions, compared with similar β-lactam compounds.
    Notes: Beschrieben wird die Synthese von erstmals dargestellten 8-Oxo-1,3-diazabicyclo[4.2.0]oct-2-en-2-carbonsäureestern 1 und ihre erhöhte Reaktivität im Vergleich zu ähnlichen β-Lactamverbindungen unter physiologischen Bedingungen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870848
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    Umsetzungen von 4-Chromon-3-sulfonsäure-phenylester mit methylenaktiven Verbindungen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 549-550 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Phenyl 4-Chromone-3-sulfonate with Methylene Active CompoundsThe methylene active compounds 2a-c undergo with phenyl 4-chromone-3-sulfonate (1) ring transformations to give the benzoxathiinopyridones 5a-c.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870375
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    Masthead (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870701
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    Racemattrennung von Propafenon und Diprafenon, Konfiguration der Propafenon-Enantiomeren (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 561-563 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical Resolution of Propafenone and Diprafenone, Configuration of Propafenone EnantiomersThe chiral antiarrhythmic drugs propafenone (rac-1) and diprafenone (rac-3) were resolved by fractional crystallization of the diastereoisomeric salts with optically active di-O, O′-p-toluoyltartaric acid and tartaric acid, respectively. Derivatization with (+)-1-phenylethyl isocyanate and analytical separation of the diastereoisomers 2 and 4 by HPLC confirmed the optical purity of the enantiomers. CD spectra of (+)- and (-)-propafenone as copper complexes established the absolute configuration: (-)-1 is R-, (+)-1 S-configurated.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870379
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    Ungewöhnliche Reaktion zu Glycosylurethanen bei einer Glycopeptidsynthese (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 577-581 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Unusual Reaction to Glycosyl Urethanes During a Synthesis of GlycopeptidesReaction of the disaccharide halide 1 with N-(3,5-dimethoxy-α,α-dimethylbenzyloxycarbonyl)-L-serine benzyl ester (5) unexpectedly yields the glycosyl urethane 10. Glycosidation of 5 predominantly occurs at the urethane oxygen and not at the free hydroxy group of L-serine. During the formation of 10 the β-hydroxy group of serine is converted into a 3,5-dimethoxy-α,α-dimethylbenzyl ether.
    Notes: Die Umsetzung des Disaccharidhalogenids 1 mit N-(3,5-Dimethoxy-α,α-dimethylbenzyloxycarbonyl)-L- serin-benzylester (5) führt unerwartet zum Glycosylurethan 10. Im Derivat 5 wird bevorzugt der Urethansauerstoff und nicht die freie OH-Gruppe des L-Serins glycosidiert. Während der Reaktion zu 10 erfolgt Überführung der β-OH-Gruppe des Serins in einen (3,5-Dimethoxy-α,α-dimethylbenzyl)ether.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870703
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    Eine neue Darstellung von Aminosäure-diphenylmethylester und ihr Einsatz für die Peptidsynthese (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 633-635 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Novel Preparation of Amino Acid Diphenylmethyl Esters and Their Application in Peptide SynthesisTrityl amino acid diphenylmethyl esters 2 were prepared by Mitsunobu condensation of tritylamino acids 1 with diphenylmethanol using excess triphenylphosphane and diethyl azodicarboxylate. The esters 2 were converted into the corresponding p-toluenesulfonates 3 on treatment with p-toluenesulfonic acid. The removal of the N-trityl group in the presence of the diphenylmethyl ester group is studied by the preparation of leucineenkephalin (12). Best selectivity is obtained when 1-hydroxybenzotriazole in trifluoroethanol is used as detritylation reagent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870711
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    Arguticin, a New Sesquiterpene from Pluchea arguta (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 643-644 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In addition to the already known sesquiterpene, plucheinol (2), the new eudesmane sesquiterpene arguticin (1) have been isolated from the whole plant of Pluchea arguta. Their structures have been elucidated by means of spectral studies and correlation with other sesquiterpenes of similar structure. Arguticin (1) contains a hydroperoxy group at C-11 and a 3α-hydroxy group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870714
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    Masthead (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870801
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  • 136
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    Synthese von Elaeocarpus-Alkaloiden durch cyclisierende Imid-Olefinierung (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 649-654 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Elaeocarpus Alkaloids Using Cyclizing Imide OlefinationsThe indolizine 3b has been synthesized by intramolecular Wittig reaction of 13a and subsequent acylation. Elaeocarpus alkaloids were obtained by reduction of 3b with LiAlH4 and subsequent oxidation.
    Notes: Das Indolizinderivat 3b wurde durch intramolekulare Wittig-Reaktion von 13a und anschließende Acylierung erhalten. Reduktion von 3b mit LiAlH4 und nachfolgende Oxidation führt zu Elaeocarpus-Alkaloiden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870802
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  • 137
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    Synthesewege zu 1-substituierten Butadienylphosphonaten (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 661-664 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthetic Routes to 1-Substituted ButadienylphosphonatesThe synthesis of 1-substituted butadienylphosphonates 5 was attempted on three routes. The easily polymerizing butadienes are generally accessible from the stable phosphonates 4 by seleninic acid elimination.
    Notes: Die Synthese 1-substituierter Butadienylphosphonate 5 wurde auf drei Wegen versucht. Dabei zeigte sich, daß die polymerisationsfreudigen Butadiene aus den stabilen Phosphonaten 4 durch Seleninsäureeliminierung schnell und bequem zugänglich sind.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870804
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  • 138
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    Chemistry and Stereochemistry of Iridoids, X. Enantiomerically Pure Hexahydropentalene Derivatives - Building Units for the Synthesis of Cyclopentanoid Natural Products (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 679-682 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemie und Stereochemie der Iridoide, X. - Enantiomerenreine Hexahydropentalen-Derivate. - Bausteine zur Synthese von cyclopentanoiden NaturstoffenEs wird die Synthese der enantiomerenreinen Hexahydropentalen-Derivate 5a-5e aus dem Iridoidglucosid Catalpol beschrieben. Mit dem kristallinen Camphansäureester 5e wird die in der Literatur angegebene absolute Konfiguration des durch Racematspaltung hergestellten (1α,3aβ,6aβ)-1,2,3,3a,4,6a-Hexahydro-1-pentalenols (5d) bestätigt.
    Notes: The synthesis of the enantiomerically pure hexahydropentalene derivatives 5a-5e starting from the iridoid glucoside catalpol is described. The absolute configuration reported for (1α,3aβ,6aβ)-1,2,3,3a,4,6a-hexahydro-1-pentalenol (5d), which has been obtained by optical resolution, is confirmed by preparation of the crystalline camphanate 5e.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870807
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  • 139
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    Einstufige stereoselektive Synthesen von Cyclopentanol-Derivaten aus 1,5-Anhydro-2,3-O-benzyliden-β-D-ribofuranose (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 683-686 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: One-Step Stereoselective Syntheses of Cyclopentanol Derivatives from 1,5-Anhydro-2,3-O-benzylidene-β-D-ribofuranose1,5-Anhydro-2,3-O-benzylidene-β-D-ribofuranose (1) reacts with butyllithium to give 3,4-benzylidene-1,6-dideoxy-6-C-propyl-α-D-ribo-hexulofuranose (6a). 1L-2,3-O-Benzylidene-1-C-butyl-1,2,3/4-cyclopentanetetrol (5) is formed as a by-product. The analogous reaction with butyllithium yields the corresponding 1,6-dideoxy-hexulose 6b. Reactions of 1,5-anhydro-2,3-O-benzylidene-β-D-lyxofuranose (7) with n-butyl- or methyllithium lead to 8a, b, the enantiomers of 6a, b. Reaction of 1 with lithium diisopropylamide gives 2L-2,3-O-benzylidene-2,3/4-trihydroxycyclopentanone (3 + H⊕). From 1,6-anhydro-3,4-O-isopropylidene-β-D-altropyranose (9) is obtained 2L-2,3-O-isopropylidene-2,3,5/4-tetrahydroxycyclohexanone (10).
    Notes: 1,5-Anhydro-2,3-O-benzyliden-β-D-ribofuranose (1) reagiert mit n-Butyllithium zu 3,4-O-Benzyliden-1,6-didesoxy-6-〈C-Propyl-α-L-ribo-hexulofuranose (6a). Als Nebenprodukt entsteht 1L-2,3-O-Benzyliden-1-C-butyl-1,2,3/4-cyclopentantetrol (5). Die analoge Reaktion mit Methyllithium ergibt die entsprechende 1,6-Didesoxyhexulose 6b. Umsetzungen von 1,5-Anhydro-2,3-O-benzyliden-β-D-lyxofuranose (7) mit Butyl- oder Methyllithium führen zu 8a, b, den Enantiomeren von 6a, b. Reaktion von 1 mit Lithiumdiisopropylamid ergibt 2L-2,3/4-trihydroxycyclopentanon (3 + H⊕). Aus 1,6-Anhydro-3,4-O-Isopropyliden-β-D-altropyranose (9) wird analog 2L-2,3-O-Isopropyliden-2,3,5/4-tetrahydroxycyclohexanon (10) erhalten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870808
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  • 140
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    Polycylen aus 1,5-Cyclooctadien und Chlorcyanketen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 701-704 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polycycles from 1,5-Cyclooctadiene and ChlorocyanoketeneChlorocyanoketene adds to cyclohexene and cyclooctene stereoselectively to give 1 or 2; 1,5-cyclooctadiene, however, yields a four-component mixture of 3a, b and 4a, b. Cyclooctatetraene reacts with the ketene differently to yield 5. Favorskii reactions of 1-3 lead to bicyclic compounds carrying carboxylic groups at bridgehead carbons (6a, b; 7a, b; 8a, b). The diazoketones accessible from 6a or 6b, respectively, give C—H insertion products (13a, b) and intramolecular cyclopropanation products (14a, b) when decomposed in the presence of RhII.
    Notes: Chlorcyanketen addiert sich stereoselektiv an Cyclohexen und Cycloocten zu 1 und 2. Mit 1,5-Cyclooctadien bildet sich jedoch ein Vierkomponenten-Gemisch von 3a, b und 4a, b. Cyclooctatetraen vereinigt sich mit dem Keten zu 5. Favorskii-Reaktionen von 1-3 führen zu Bicyclen mit Carboxygruppen am Brückenkopf (6a, b; 7a, b; 8a, b). Die aus 6a sowie 6b zugänglichen Diazoketone liefern bei der Zersetzung in Gegenwart von RhII Gemisch von C—H-Einschiebungs-Produkten (13a, b) und intramolekularen Cyclopropanierungs-Produkten (14a, b).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870811
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  • 141
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    Insect Growth Regulators, XVIII. The Syntheses of Doxyl Nitroxides Juvenoids (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 709-710 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Insekten-Wachstumsregulatoren, XVIII. - Synthesen von Doxyl-Nitroxid-JuvenoidenAus Pseudoionon (1) wurden die beiden Juvenoide 7a und 7b hergestellt.
    Notes: Starting from pseudoionone (1), the juvenoids 7a and 7b were synthesized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870813
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  • 142
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    2-Chloro-4,5-dihydroimidazole, III. Synthesis, Reactions, and Crystal Structure of 2-(Alkylthio)-7,8-dihydroimidazo[1,2-a]-1,3,5-triazine-4(6H)-thiones (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 721-724 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of 2-chloro-4,5-dihydroimidazolium hydrogen sulfate (1) with ammonium thiocyanate results in the formation of 7,8-dihydroimidazo[1,2-a]-1,3,5-triazine-2,4(3H,6H)-dithione (3), which undergoes selective alkylation under alkaline conditions to give 2-(alkylthio)-7,8-dihydroimidazo[1,2-a]-1,3,5-triazine-4(6H)-thiones 4a-f. 2-Methylthio derivative 4a serves as a substrate for the synthesis of 2,3-dihydroimidazo[1,2-a]-[1,2,4]triazolo[4,3-c][1,3,5]triazine-5(6H)-thione (7). The structure of 4c is proved by X-ray analysis.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870816
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  • 143
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    Elucidation of a Side Reaction During Acylation of Primary Amines with Fatty Acid Chlorides (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 895-899 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the presence of a tertiary base the well-known acylation of primary amines with fatty acid chlorides yields 4-alkylidene-3-alkyloxetanones 10 as byproducts, which can acylate the amino compound to give the α-alkyl-β-keto amide 11. This so far not observed side reaction has been detected for the first time during the acylation of L-cystine di-tert-butyl ester with palmitoyl chloride, however, analoguous side products may be obtained with any other amino acid ester or amino compound in general.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870846
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  • 144
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    Hexahydropyrroloindole Versuche zur Synthese von 2-Indolylthioethern (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 901-910 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hexahydropyrroloindoles - Attempts to Synthesize 2-Indolyl ThioethersThe N-[tert-butyloxycarbonyl(Boc)]tryptamine derivatives 9, 11, 12 and 19 with the functional groups CN, CONH2, CO2H, and CO2Me, respectively, in the α position to the indole ring have been synthesized. Sensitized photooxidation of 9, 12, 19, N-Boc-tryptophan (21), and N-Boc-tryptamine (22) affords the hexahydropyrroloindoles 23-27, in the case of 11 the ring closure occurs at the amine nitrogen to give the ketone 28, N-Boc-homotryptamine (31) yields the hexahydropyridoindole 32, whereas no azetidine formation from 2-(3-indolyl)glycine (36) is observed. The oximes 34a and 34b, intermediates in the synthesis of 36, have been separated chromatographically and characterized NMR spectroscopically as E and Z isomers, respectively. - Attempts to introduce with cysteine derivatives a thioether group in position 2 of the compounds described above, failed. 21, 22, 26, 27, and N-Boc-2-(3-indolyl)propylamine (43), bearing a methyl group in the α position to the indole ring, and its photooxidation product 44 show only thin-layer chromatographically detectable thioether formation.
    Notes: Die N-[tert-Butyloxycarbonyl(Boc)]tryptaminderivate 9, 11, 12 und 19 mit den funktionellen Gruppen CN, CONH2, CO2H bzw. CO2Me in α-Stellung zum Indolring werden synthetisiert. Die sensibilisierte Photooxidation von 9, 12, 19, N-Boc-tryptophan (21) und N-Boc-tryptamin (22) liefert die Hexahydropyrroloindole 23-27, im Falle von 11 erfolgt der Ringschluß über den Amidstickstoff zum Keton 28, N-Boc-homotryptamin (31) ergibt das Hexahydropyridoindol 32, während 2-(3-Indolyl)glycin (36) kein isolierbares Azetidinderivat bildet. Die Oxime 34, Zwischenprodukte bei der Synthese von 36, konnten chromatographisch getrennt und NMR-spektroskopisch der E-Reihe (34a) und Z-Reihe (34b) zugeordnet werden. - Versuche, bei den dargestellten Verbindungen in 2-Position mit Cysteinderivaten eine Thioethergruppierung einzuführen, mißlangen. 21, 22, 26 und 27 sowie N-Boc-2-(3-indolyl)propylamin (43), das in α-Stellung zum Indolring eine Methylgruppe trägt, und sein Photooxidationsprodukt 44 zeigten nur dünnschichtchromatographisch nachweisbare Thioetherbildungen.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870847
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  • 145
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    A Convenient and Single-Step Synthesis of Substituted 12H-Quinoxalino-[2,3-b][1,4]benzothiazines and -benzoxazines (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 921-925 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Eine bequeme Einstufen-Synthese für substituierte 12H-Chinoxalino[2,3-b][1,4]benzothiazine und -benzoxazine2,3-Dichlorchinoxalin (4) und die 2-Aminothiphenole 1a-h oder deren Zink-mercaptide 3a-h reagieren in alkalischem Dimethylformamid oder saurem Medium unter Cyclokondensation mit guten Ausbeuten zu entsprechenden 12H-Chinoxalino-[2,3-b][1,4]benzothiazinen 7a-h. Analog liefert die Umsetzung substituierter 2-Aminophenole 2 in basischem DMF die 12H-Chinoxalino[2,3-b][1,4]benzoxazine 7i-k. Ferner wurden Acetylderivate von 7a-k hergestellt.
    Notes: Cyclocondensation of 2,3-dichloroquinoxaline (4) and the 2-aminothiophenols 1a-h or their zinc mercaptides 3a-h in the presence of alkaline dimethylformamide or in acidic medium afforded the corresponding 12H-quinoxalino[2,3-b][1,4]benzothiazines 7a-h in excellent yields. Similarly, the reaction of 4 with substituted 2-aminophenols 2 in the presence of base using dimethylformamide as solvent gave the 12H-quinoxalino[2,3-b][1,4]-benzoxazines 7i-k. Acetyl derivatives of 7a-k were prepared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870849
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  • 146
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    Retinoide, X. Ein neuer Weg zu 5-Ethyl-18-norretinoiden (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 943-947 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Retinoids, X. - A Novel Way to 5-Ethyl-18-norretinoidsThe synthesis of 5-ethyl-18-norretinal (2) is described; the key step is the cyclization of acrolein (3) with 2-methyl-3-hexanone (4) to 2-ethyl-6,6-dimethyl-2-cyclohexen-1-one (5).
    Notes: Die Synthese von 5-Ethyl-18-norretinal (2) wird beschrieben; der Schlüsselschritt ist die Cyclisierung von Acrolein (3) mit 2-Methyl-3-hexanon (4) zu 2-Ethyl-6,6-dimethyl-2-cyclohexen-1-on (5).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870852
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  • 147
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    Arylsubstituierte Purine, I. Synthese von 7-Phenylguanin und 2-substituierten 7-Arylhypoxanthinen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 957-960 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aryl-Substituted Purines, I. - Synthesis of 7-Phenylguanine and of 2-Substituted 7-ArylhypoxanthinesThe synthesis of 7-phenylguanine (2) by cyclisation reaction of ethyl 4-amino-1-phenyl-5-imidazolecarboxylate (1a) with cyanamide is described. This reaction is the first and hitherto only synthetic approach to a hypothetical base adduct the significance of which is discussed in relation to the carcinogenesis of benzene. Moreover, the 2-substituted 7-arylhypoxanthines 4a-e have been prepared by reaction of ethyl 1-aryl-4-amino-5-imidazole-carboxylates 1a-c with thioamides 3a-c. Formic acid proved to be the best catalyst. By this new procedure starting compounds for the development of a radioimmuno assay for the trace analysis of 2 can be prepared in good yields.
    Notes: Die Synthese von 7-Phenylguanin (2) durch Cyclisierung von 4-Amino-1-phenyl-5-imidazolcarbonsäure-ethylester (1a) mit Cyanamid wird beschrieben. Die Reaktion gewährt den ersten und bisher einzigen Zugang zu einem hypothetischen Basenaddukt, dessen Bedeutung für die Benzolkanzerogenese zur Diskussion steht. Darüber hinaus wurden die 2-substituierten 7-Arylhypoxanthine 4a-e durch Reaktion von 1-Aryl-4-amino-5-imidazolcarbonsäure-ethylestern 1a-c und Thioamiden 3a-c dargestellt. Als bester Katalysator hat sich Ameisensäure erwiesen. Dieses neue Verfahren bietet einen guten Zugang zu Ausgangsverbindungen für die Entwicklung eines Radioimmunoassays zum Spurennachweis von 2.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870854
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    1,2-Carbonylverschiebung unter Dehydrierung in 1,5-Dimethylbicyclo[3.3.0]octan-3,7-dion (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 965-970 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,2-Carbonyl Transposition with Concomittant Dehydrogenation in 1,5-Dimethylbicyclo[3.3.0]octane-3,7-dioneImprovements are reported for the conversion of the diketone 10 into the mixture of dienes 14 and 15 (45:55). Photo-oxygenation of the dienes produces the allylhydroperoxides 17 and 18 or, after prolonged reaction time, the bis(allylhydroperoxides) 21 and 22. Acetic anhydride and pyridine dehydrate the allylhydroperoxides in solution affording the dienones 16 and 19 and the dienediones 20 and 12, respectively. The latter are separated through flash chromatography.
    Notes: Photooxygenierung des Gemischs der Diene 14 und 15 (45:55), deren Herstellung aus dem Diketon 10 verbessert wird, ergibt die Allylhydroperoxide 17 und 18 oder, nach längerer Reaktionsdauer, die Bis(allylhydroperoxide) 21 und 22. Diese werden in Lösung mit Acetanhydrid und Pyridin zu den Dienonen 16 und 19 bzw. den Diendionen 20 und 12 dehydratisiert. Die Diendione werden durch Blitzchromatographie getrennt.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870856
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    Functionalization of 3,5,6-trialkyl-4-hydroxy-2-pyrones in the 6-α position (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 987-990 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Funktionalisierung von 3,5,6-Trialkyl-4-hydroxy-2-pyronen in der 6-α-StellungDie Darstellung des 6-Ethyl-4-hydroxy-3,5-dimethyl-2-pyrons (5) wurde verbessert. Eine selektive Funktionalisierung in der 6-α-Stellung gelang nach Überführung in die Acetoxy-Verbindung 11 durch Oxidation mit Selendioxid zum Alkohol 13. Dieser ließ sich zum Keton 17 oxidieren, oder in die Brom-Verbindung 12 umwandeln, aus der andere 2-Pyrone mit einem Heterosubstituenten in der 6-α-Stellung gewonnen wurden.
    Notes: The preparation of 6-ethyl-4-hydroxy-3,5-dimethyl-2-pyrone (5) has been improved. Selective functionalization in the 6-α position of the pyrone 5 was possible by converting it into the 4-acetoxy compound 11 followed by selenium dioxide oxidation to the alcohol 13. The latter could be oxidized to the ketone 17 or be converted via the bromide 12 into other 2-pyrones having a hetero substituent in the 6-α position.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870859
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  • 150
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    Optical Resolution of (±)-2,3-Dihydro-2-phenyl-4H-1-benzothiopyran-4-one (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 1007-1008 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical resolution of the title compound was achieved using the optically active reagent (+)-5-(α-phenethyl)semioxamazide (2).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870862
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    Modifizierung von Kieselgel mit Weinsäurederivaten hoher Stereoisomerenreinheit und Charakterisierung durch Festkörper-13C-NMR-CP-MAS-Spektroskopie (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 991-995 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Modification of Silica Gel by Derivatives of Tartaric Acid of High Stereoisomeric Parity and Characterisation by Solid-State 13C-NMR-CP-MAS Spektroscopy(Dissymmetric) tartaric acid of high stereoisomeric purity (99.3% 2R,3R, 0.1% 2S,3S, and 0.6% meso, determined by GC on Chirasil-Val) is used for the synthesis of chirally modified silica phases. Two synthetic approaches have proven particularly useful for the formation of the well-suited monoalkoxytrialkylsilane functions: DCCI-mediated coupling of the carboxylic group with γ-(aminopropyl)methoxydimethylsilane, or hydrosilylation of ω-unsaturated amides [e.g., acetonide of tartaric acid bis(allylamide), 97.8% 2R,3R, 0.2% 2S,3S, and 2.0% meso] with methoxydimethylsilane. The well-defined chiral percursors are bound to the silica surface in the final step of the synthesis. Twofold monofunctional coupling of bis-functionalized derivatives leads to particularly stable stationary phases of high chemical uniformity, as demonstrated by solid-state 13C-NMR-CP-MAS spectroscopy.
    Notes: Auf der Basis von (dissymmetrischer) Weinsäure hoher Stereoisomerenreinheit (99.3% 2R,3R, 0.1% 2S,3S und 0.6% meso, laut GC an Chirasil-Val) werden chiral modifizierte Kieselgelphasen synthetisiert. Zwei Verfahren sind zum Aufbau der vorteilhaften Monoalkoxytrialkylsilan-Funktionen besonders geeignet: DCCI-Kupplung der Carboxylgruppe mit γ-(Aminopropyl)methoxydimethylsilan oder Hydrosilylierung von ω-ungesättigten Amiden [z. B. ein Acetonid des Weinsäure-bis(allylamids), 97.8% 2R,3R, 0.2% 2S,3S und 2.0% meso] mit Methoxydimethylsilan. Erst im letzten Reaktionsschritt werden die vollständig charakterisierten chiralen Vorstufen an die Kieselgeloberfläche gebunden. Die zweifache monofunktionelle Anbindung von bisfunktionalisierten Derivaten führt zu sehr stabilen, einheitlich gebauten stationären Phasen, wie durch Festkörper-13C-NMR-CP-MAS-Spektroskopie gezeigt wird.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870860
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  • 152
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    Mono- und Bis(aryl/alkylthio)butenine sowie Bis- und Tris(aryl/alkylthio)butadiene aus Pentachlorbutadien und Hexachlorbuten (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 1009-1011 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mono- and Bis(aryl/alkylthio)butenynes, Bis- and Tris(aryl/alkylthio)butadienes from Pentachlorobutadiene and HexachlorobuteneCompounds 3b, 3e-g, 4d, 4e-g, 5b, 5d, 6c, 6e-g, 7c, and 9e-g have been obtained from 2H-pentachlorobutadiene (1) and thiolates in water-containing ethanol solutions at room temperature. Hexachlorobutene (8) and alkanethiolates give compounds 3e, 4e, and 9e-g. Compounds 11b, 3b, 5b, and 6b could be prepared from hexachlorobutene (10) under the same conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870863
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  • 153
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    Verbesserte Synthese von 6β, 7β-Epoxy-17β-hydroxy-3-oxo-4,6-pregnadien-21-carbonsäure-γ-lacton (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 1015-1016 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Improved Synthesis of 6β, 7β-Epoxy-17β-hydroxy-3-oxo-4,6-pregnadiene-21-carboxylic Acid γ-LactoneThe title compound 2, a metabolite of canrenone (1) in rats, is synthesized starting from 1 via derivative 3c in a 25-g scale in a much shorter time and higher yield than in the literature cited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870865
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  • 154
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    Terpene und Terpen-Derivate, XXI. Synthese von rac-4,5-Dihydro-β-curcumen-4,5-diol (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 1013-1014 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Terpenes and Terpene Derivatives, XXI. - Synthesis of rac-4,5-Dihydro-β-curcumene-4,5-diolHydrolysis of the β-curcumene monoepoxide 1 afforded the title compound 2. - A second way started from the epoxy ketone 6. Hydrolysis (→ 7), formation of the THP ethers (→ 8, → 9), and reaction with homoprenyllithium leads to the allylic alcohol 3. After further protection (→ 4), Birch reduction, and subsequent hydrolysis a 1:4 mixture of the diols 2 and (E/Z)-11 was isolated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870864
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  • 155
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    Synthesis of N-(Glucopyranosid-3-yl)-D- and -L-alanyl-D-isoglutamine and Related Glycodipeptides (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 1017-1020 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von N-(Glucopyranosid-3-yl)-D- und -L-alanyl-D-isoglutamin und verwandten GlycodipeptidenEs wurden sechs Glucodipeptide dargestellt, bei denen der D-Lactyl-L-alanyl-Rest des immunoadjuvanten Muramyldipeptids durch D-Ala, L-Ala und Gly ersetzt wurde. Die Kupplungsreaktion von Benzyl-2-acetamido-4,6-O -benzylidene-3-[R-(1-carboxyethyl)amino]-2,3-dideoxy-α-D-glucopyranosid 8, 9 bzw. 10 mit D-Isoglutamin-methylester und D-Glutamin-methylester und nachfolgende Hydrogenolyse ergab die entsprechenden N-(2-Acetamino-2,3-dideoxy-D-glucopyranosid-3-yl)-Derivate von D-Ala-D-iso-Gln-OMe (14), L-Ala-D-isoGln-OMe (15), Gly-D-isoGln-OMe (16), D-Ala-D-Gln-OMe (20), L-Ala-D-Gln-OMe (21) und Gly-D-Gln-OMe (22).
    Notes: Six glucodipeptides, in which the D-lactyl-L-alanyl residue of the immunoadjuvant myramyl dipeptide is replaced by D-Ala, L-Ala, and Gly, have been synthesized. Coupling of benzyl 2-acetamido-4,6-O-benzylidene-3-[R-(1-carboxyethyl)amino-, -S-(1-carboxyethyl)amino-, and -(carboxymethyl)amino]-2,3-dideoxy-α-D-glucopyranosides 8,9, and 10, respectively, with D-isoglutamine methyl ester and D-glutamine methyl ester followed by hydrogenolysis afforded the corresponding N-(2-acetamido-2,3-dideoxy-D-glucopyranosid-3-yl) derivatives of D-Ala-D-isoGln-OMe (14), L-Ala-D-isoGln-OMe (15), Gly-D-isoGln-OMe (16), D-Ala-D-Gln-OMe (20), L-Ala-D-Gln-OMe (21), and Gly-D-OMe (22).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870866
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  • 156
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    Einsatz von Trt- und Fmoc-Gruppen zum Schutz polyfunktioneller α-Aminosäuren (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 1025-1030 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Application of the Trt and Fmoc Groups for the Protection of Polyfunctional α-Amino AcidsSimple methods for the preparation of ditrityl amino acids 3 and their application for the synthesis of the peptides 9-27 are described. Selective detritylation of 3 and of the synthesized ditrityl peptides is achieved with 1% trifluoroacetic acid in dichloromethane. The resulting Nα-detritylated amino acids 5 were converted into the corresponding fluorenylmethoxycarbonyl amino acids 6 under Schotten-Baumann conditions using fluorenylmethyl chloroformate.
    Notes: Es werden einfache Methoden zur Darstellung von Ditrityl-Aminosäuren 3 und ihre Anwendung zur Synthese der Peptide 9-27 beschrieben. Selektive Nα-Detritylierung wird bei 3 und bei den synthetisierten Ditrityl-Peptiden durch Einwirkung von 1proz. Trifluoressigsäure in Dichlormethan erzielt. Die an der Seitenkette detritylierten Aminosäuren 5 lassen sich unter Schotten-Baumann-Bedingungen durch Reaktion mit Fluorenylmethylchlorformat in die entsprechenden Fluorenylmethoxycarbonyl-Aminosäuren 6 überführen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870868
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  • 157
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    Synthetische Anthracyclinone, 35. Synthese des Nogalamycin-Aglycons (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 1037-1043 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthetic Anthracyclinones, 35. - Synthesis of the Nogalamycin AglyconThe keto ester 13 is predominantly cyclized to the 1,2-cis-hydroxy ester 16 under aprotic conditions. Dimethyl ether 16 is split to 17. Hydroxylation of 17 by bromination and hydrolysis affords the nogalamycin aglycon 19 with 2,4-trans-hydroxy groups.
    Notes: Der Ketoester 13 cyclisiert unter aprotischen Bedingungen bevorzugt zum 1,2-cis-Hydroxyester 16, der zu 17 gespalten wird. Hydroxylierung von 17 durch Bromierung und Solvolyse führt zum Nogalamycin-Aglycon 19 mit 2,4-trans-Hydroxygruppen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870870
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  • 158
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    Neue Reagenzien zur Entkomplexierung kupfergeschützter Aminosäuren (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 1115-1116 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Reagents to Decompose Copper Complexes of Amino AcidsThe use of N,N-dialkyl-N′-(benzoyl)thioureas in ethanol is an effective method to decompose copper complexes of amino acids. The reaction gives optimal yields, and no racemisation is observed. Furthermore, the recovery of the thiourea derivatives is an important advantage of this method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870882
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  • 159
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    Ansa-Seco-Steroide (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 1095-1099 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ansa-Seco SteroidsDiels-Alder adducts of monosubstituted acetylene compounds to ergosterol acetate (6) in a retro reaction give rise to aromatic ansa compounds of type 8a. The regioselectivity of the propargylic aldehyde addition is proven by an X-ray structure determination of dimethyl acetal 8b. Structures of other cycloaddition products are correlated to this aldehyde by chemical transformations.
    Notes: Durch Retro-Dien-Reaktion einiger Diels-Alder-Addukte des Ergosterolacetats (6) mit monosubstituierten Acetylenverbindungen werden aromatische Ansa-Verbindungen vom Typ 8a gewonnen. Die Regioselektivität der Addition von Propargylaldehyd folgt aus der Röntgenstrukturanalyse des kristallinen Dimethylacetals 8b. Andere Addukte können chemisch mit diesem Produkt korreliert werden.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870878
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  • 160
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    Spaltung der Sauerstoffbrücke in 8-Oxabicyclo[3.2.1]octan-3-onen und -oct-6-en-3-onen durch Trimethylsilyltrifluormethansulfonat (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 1-5 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cleavage of the Oxygen Bridge in 8-Oxabicyclo[3.2.1]octan-3-ones and -oct-6-en-3-ones by Trimethylsilyl TrifluoromethanesulfonateThe 8-oxabicyclo[3.2.1]oct-6-en-3-ones 1a-c react with trimethylsilyl trifluoromethanesulfonate/triethylamine (TMSOTf/NEt3) to give tropones. The bicyclic compounds 5, hydrogenated at the 6,7-double bond, are cleaved by TMSOTf/NEt3 to form 1,6-bis(trimethylsiloxy)-1,3-cycloheptadienes 6 and the double bond isomers 7a, 8e. Cycloheptenones are obtained by methanolysis of the trimethylsilyl dienol ethers.
    Notes: Die 8-Oxabicyclo[3.2.1]oct-6-en-3-one 1a-c reagieren mit Trimethylsilyltrifluormethansulfonat/Triethylamin (TMSOTf/NEt3) zu Troponen. Aus den an der 6,7-Doppelbindung hydrierten Bicyclen 5 entstehen mit TMSOTf/NEt3 die 1,6-Bis(trimethylsiloxy)-1,3-cycloheptadiene 6 neben Doppelbindungsisomeren 7a, 8e. Durch Methanolyse der Trimethylsilyldienolether lassen sich Cycloheptenone gewinnen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870102
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  • 161
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    2-Amino-2′-desoxytubercidin und verwandte Pyrrolo[2,3-d]pyrimidinyl-2′-desoxyribofuranoside (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 15-19 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 2-Amino-2′-deoxytubercidin and Related Pyrrolo[2,3-d]pyrimidinyl 2′-DeoxyribofuranosidesPhase-transfer glycosylation of 2-amino-4-chloro-7H-pyrrolo-[2,3-d]pyrimidine (4a) with 1-chloro-3,5-di-O-(p-toluoyl)-α-D-erythro-pentofuranose (7) yields in a regio- and diastereoselective reaction the crystalline condensation product 5a. Nucleophilic displacement of the 4-chloro substituent of 5a or the unprotected nucleoside 2b opens a route to 2-amino-2′-deoxytubercidin (1) or the thionucleoside 3a. The anomers 8 and 9 of 2-deoxy-1,3,5-triO-(p-toluoyl)-D-erythro-pentofuranose were isolated from the glycosylation reaction carried out in the absence of the nucleobase.
    Notes: Phasentransferglycosylierung von 2-Amino-4-chlor-7H-pyrrolo-[2,3-d]pyrimidin (4a) mit 1-Chlor-3,5-di-O-(p-toluoyl)-α-D-erythro-pentofuranose (7) führt regio- und diastereoselektiv zum kristallinen Verknüpfungsprodukt 5a. Dessen 4-Halogensubstituent oder der des ungeschützten Nucleosids 2b ist nucleophil substituierbar, wodurch 2-Amino-2′-desoxytubercidin (1) und das Thionucleosid 3a zugänglich werden. In Abwesenheit der Nucleobase konnten aus dem Glycosylierungsansatz die anomeren 2-Desoxy-1,3,5-tri-O-(p-toluoyl)-D-erythro-pentofuranosen 8 und 9 isoliert werden.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870104
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  • 162
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    Constituents of the Essential Oil of Strobilanthes auriculatus (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 21-28 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Inhaltsstoffe des ätherischen Öls aus Strobilanthes auriculatusDreiundzwanzig Inhaltsstoffe des ätherischen Öls aus St. auriculatus wurden identifiziert. Isoborneol (6), dessen Isobutyrat 10 und 8-(Isobutyryloxy)isobornyl-isobutyrat (22) sind die Hauptbestandteile (zusammen 82%). 22 und weitere oxidierte Isoborneol-Derivate 15, 17-19, 21 sind neue natürlich vorkommende Verbindungen.
    Notes: Twenty-three constituents of the essential oil of St. auriculatus could be identified. Isoborneol (6), its isobutyrate 10, and 8-(isobutyryloxy)isobornyl isobutyrate (22) are the main components (altogether 82%). 22 and further oxidized isoborneol derivatives 15, 17-19, 21 are new naturally occurring compounds.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870105
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  • 163
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    Asymmetrische Synthese von α-Aminophosphonsäuren, III. Asymmetrische Synthese von (S)-(1-Aminoalkyl)phosphonsäure-diethylestern unter Verwendung von (+)-Campher als chiralem Hilfsreagens (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 45-49 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetric Synthesis of α-Aminophosphonic Acids, III1). - Asymmetric Synthesis of Diethyl (S)-(1-Aminoalkyl)phosphonates Using (+)-Camphor as Chiral AuxiliaryThe lithium derivative 4 of the Schiff base 3, obtained from (+)-camphor (1) and diethyl (aminomethyl)phosphonate (2), reacts diastereoselectively with alkyl halides to give the products 5. The asymmetric inductions vary between 11% (for methyl iodide) to ca. 95% (for allyl or benzyl bromide). Hydrolysis of the compounds 5 yields the diethyl (S)-(1-aminoalkyl)phosphonates 6 that can be hydrolyzed to give the (1-aminoalkyl)phosphonic acids 7.
    Notes: Das Lithiumderivat 4 der Schiff-Base 3 aus (+)-Campher (1) und (Aminomethyl)phosphonsäure-diethylester (2) reagiert mit Alkylhalogeniden diastereoselektiv zu den Produkten 5. Die asymmetrischen Induktionen variieren von 11% (Methyliodid) bis ca. 95% (für Allyl- oder Benzylbromid). Die Hydrolyse der Verbindungen 5 liefert die Diethyl-(S)-(1-aminoalkyl)phosphonate 6, aus denen die (S)-(1-Aminoalkyl)phosphonsäuren 7 erhältlich sind.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870108
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  • 164
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    Sila-Pharmaka, 36. Sila-Procyclidin: Eine neue Synthese sowie Untersuchungen zur peripheren und zentralen anticholinergen Wirkung (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 51-57 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sila-Pharmaca, 361). - Sila-Procyclidine: A New Synthesis as well as Investigations of the Peripheral and Central Anticholinergic ActivityStarting with Cl3SiCH2Cl, sila-procyclidine (1b) as well as its derivatives 2b (sila-trihexyphenidyl), 3b, and 4b (sila-cycrimine) were prepared by a new six-step synthesis with a total yield of 16 (1b), 19 (2b), 8 (3b) and 7% (4b), respectively. - Comparative in vivo investigations (mice, per os administration) with respect to the peripheral and central anticholinergic activity have shown that the silicon compound 1b is advantageous over the carbon analogue 1a (procyclidine).
    Notes: Sila-Procyclidin (1b) sowie dessen Derivate 2b (Sila-Trihexyphenidyl), 3b und 4b (Sila-Cycrimin) wurden - ausgehend von Cl3SiCH2Cl - durch eine neue, sechsstufige Synthese mit einer Gesamtausbeute von 16 (1b), 19 (2b), 8 (3b) bzw. 7% (4b) dargestellt. - Vergleichende in-vivo-Untersuchungen (Maus, per-os-Applikation) hinsichtlich der peripheren und zentralen anticholinergen Wirkung haben gezeigt, daß die Silicium-Verbindung 1b dem Kohlenstoff-Analogon 1a (Procyclidin) überlegen ist.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870109
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  • 165
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    Isolierung farblosen Benzolhexamins (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 265-265 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isolation of Colourless BenzenehexamineFor the first time benzenehexamine (2) has been prepared as colourless needles in good yield by catalytic hydrogenation of 2,4,6-trinitro-1,3,5-benzenetriamine and workup of its aqueous solution under argon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870319
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  • 166
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    Dimere Naphthochinone, XX. Partialsynthese von Actinorhodin (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 297-304 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dimeric Naphthoquinones, XX. - Partial Synthesis of ActinorhodineMethyl 3,4-dihydro-9,10-dihydroxy-6-methoxy-1-methyl-1H-naphtho[2,3-c]pyran-3-acetate (10b), obtainable by diazomethane degradation of deacetylanhydronaphthocyclinone methyly ester (13) and monomethylation, is dimerised leading to dideoxyactinorhodine dimethyl ester (8d). Cer(IV) hydroxylation of the latter yields (1S,1′S,3R,3′R)-actinorhodine (1c), the enantiomer of the quinone antibiotic from Actinomyces coelicolor, thus confirming the 8,8′-connection in 1a. On a similar way, nanaomycin A (7c) gives 9c, the enantiomer of a potential intermediate of the biosynthesis of 1a.
    Notes: Der durch Diazomethan-Abbau von Desacetylanhydronaphthocyclinon-methylester (13) erhältliche 3,4,6,9-Tetrahydro-10-hydroxy-1-methyl-6,9-dioxo-1H-naphtho[2,3-c]pyran-3-essigsäuremethylester (6d) läßt sich über seinen Hydrochinon-monomethylether 10b oxidativ zu Didesoxyactinorhodin-dimethylester (8d) dimerisieren; dessen Cer(IV)-Hydroxylierung führt zu (1S,1′S,3R,3′R)-Actinorhodin (1c), dem Antipoden des von Actinomyces coelicolor gebildeten Chinon-Antibioticums, und bestätigt auf diesem Wege die 8,8′-Verknüpfung in 1a. Auf ähnliche Weise erhält man aus Nanaomycin A (7c) das Enantiomere 9c einer potentiellen Zwischenstufe der 1a-Biosynthese.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870325
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  • 167
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    Synthese eines biologisch aktiven Analogons des Prostaglandins E2 (Racemat und reine Enantiomere) (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 321-326 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of a Biologically Active Analogue of Prostaglandin E2 (Racemate and Enantiomerically Pure Compounds)Transformation of 6-chloro-3-oxo-2-oxabicyclo[3.2.1]octane-8-carbaldehyde (6) by an eight-step synthesis leads to racemic (5Z,13E)-11,15-dihydroxy-16,16-dimethyl-9-oxo-18-oxa-5,13-prostadienoic acid (1) (dimoxaprost). The synthesis starts with the introduction of the ω-side chain of 1 into 6 by Horner-Emmons-Wittig reaction with the phosphonate 7. Ring cleavage and rearrangement of 8 affords enone 9a with unprotected hydroxyl group. By stereoselective reduction of 9a, diol 11a is obtained. Subsequently, 11a is converted in five steps through the “Corey synthesis” into 1. The 5-ketoprostacyclin 17 is isolated as a by-product of the Jones oxidation of 15. Finally, the synthesis of optically pure (-)-1 and (+)-1, starting with the keto acids (+)-2 and (-)-2, is described.
    Notes: Ausgehend von 6-Chlor-3-oxo-2-oxabicyclo[3.2.1]octan-8-carbaldehyd (6) wird in einer 8stufigen Synthese racemische (5Z,13E)-11,15-Dihydroxy-16,16-dimethyl-9-oxo-18-oxa-5,13-prostadiensäure (1) (Dimoxaprost) dargestellt. Im ersten Reaktionsschritt wird dazu die ω-Seitenkette von 1 mit Hilfe der Horner-Emmons-Wittig-Reaktion und dem Phosphonat 7 in 6 eingeführt. Ringöffnung und Umlagerung von 8 führt zu dem Enon 9a mit freier Hydroxylgruppe. Dessen stereospezifische Reduktion ergibt das Diol 11a, welches analog der Corey-Synthese in fünf weiteren Reaktionsschritten in 1 übergeführt wird. Das 5-Ketoprostacyclin 17 wird dabei als Nebenprodukt isoliert. Die Synthese der beiden optischen Antipoden (-)-1 und (+)-1 wird in entsprechender Weise ausgehend von den Ketosäuren (+)-2 bzw. (-)-2 durchgeführt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870328
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  • 168
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    The Use of S-Acetamidomethyl-L-cysteine in the Synthesis of Glutathione, Glutathione Fragments, and Their Amides (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 69-71 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of oxidized glutathione and of its amide with 2-amino-2-phenyl-1H-indene-1,3(2H)-dione is described. In the preparation of all peptide bonds (except for that of the tripeptide 17) and of the amide bond of compound 12, coloured active esters of 2-phenyl-1H-indene-1,3(2H)-dione are used. The acetamidomethyl (Acm) protecting group is used for the first time in the synthesis of glutathione.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870112
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  • 169
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    Masthead (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870201
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  • 170
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    Cyclit-Reaktionen, XVI. Synthese von Varianten des Valiolamins (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 439-445 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclit-Reactions, XVI. - Synthesis of Valiolamine DerivativesAddition of the anion of 5-methyl-1,3,5-dithiazinane 3 to the enone 2 gives the branched compound 4. Cleavage of the dithioacetal and reduction leads to the hydroxymethyl branched inosite derivative 6. Epoxidation of 6 yields the epoxide 10, which can be opened after benzylation to produce 14. Hydrogenolysis of 14 leads to valiolamine derivative 16. Ulose 19, obtained from 18, is converted into oximes 20 and 21 by hydroxylamine. Reduction yields the amines 22, 23, and 25. Debenzylation leads to the hydrochlorides of the valiolamine derivatives 26, 27, and 28.
    Notes: In das Enon 2 kann mit dem Anion des 5-Methyl-1,3,5-dithiazinans 3 eine Seitenkette unter Bildung von 4 eingeführt werden, aus dem nach Spaltung und Reduktion das Hydroxymethyl-verzweigte Inosit-Derivat 6 erhältlich ist. Epoxidierung von 6 führt zum Epoxid 10, das nach Benzylierung zu 12 mit Natriumazid in das Epoxidöffnungsprodukt 14 überführbar ist. Die Hydrierung von 14 ergibt das hydroxylierte Valiolamin-Derivat 16. Die aus 18 erhältliche Ulose 19 kann mit Hydroxylamin in die Oxime 20 und 21 umgewandelt werden. Die Hydrierung der Oxime führt zu den Aminen 22, 23 und 25. Nach der Entblockierung ergeben diese die Hydrochloride der drei Varianten des Valiolamins 26, 27 und 28.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870350
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  • 171
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    Stereoisomere Aromastoffe, XVI. Struktur und Eigenschaften optisch reiner 2-Methyl-4-propyl-1,3-oxathian-3-oxide (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 451-453 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereoisomeric Flavor Compounds, XVI. - Structure and Properties of Optically Pure 2-Methyl-4-propyl-1,3-oxathiane 3-OxidesOxidation of cis-2-methyl-4-propyl-1,3-oxathiane (1) by NaIO4 yields diastereomeric sulfoxides (equatorial/axial relation 3:1), which were separated by liquid chromatography. From optically pure (2S,4R)-1 the sulfoxides 2 (75%) and 3 (25%) and from (2R,4S)-1 the sulfoxides 2′ (75%) and 3′ (25%) were generated. For 3 an X-ray structure analysis was performed.
    Notes: Durch Oxidation von cis-2-Methyl-4-propyl-1,3-oxathian (1) mit NaIO4 entstehen diastereomere Sulfoxide (äquatorial/axial-Verhältnis 3:1), die flüssigkeitschromatographisch rein erhalten werden. Aus optisch reinem (2S,4R)-1 werden die Sulfoxide 2 (75%) und 3 (25%), aus (2R,4S)-1 die Sulfoxide 2′ (75%) und 3′ (25%) erhalten. Für 3 wurde eine Röntgenstrukturanalyse durchgeführt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870352
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  • 172
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    Über das Vorkommen von F-Säuren in Rinderleber und deren enzymatischen Abbau bei Gewebeverletzung (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 459-462 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Occurrence of F Acids in Cattle Liver and Their Enzymatic Degradation During Tissue DamageFuranalkanoic acids 4 (F acids) occur in liver of cattle as cholesterides and glycerides. If liver cells are damaged, the furan ring of 4 is enzymatically transformed into dioxoalkenoic acids 3 which are converted by an aldol reaction into (hydroxy-oxo-cyclopentenyl)alkanoic acids. After methylation with diazomethane they were isolated as 1 and 2.
    Notes: Furanalkansäuren 4 (F-Säuren) kommen als Cholesterin- oder Glycerinester in Rinderleber vor. Bei Zellschädigung werden diese enzymatisch sehr rasch zu Dioxoalkensäuren 3 umgesetzt, die unter Basenkatalyse cyclisieren und, nach Veresterung mit Diazomethan, als (Hydroxy-oxo-cyclopentenyl)alkansäure-methylester 1 und 2 nachgewiesen werden.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870354
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  • 173
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    Scorpiolid, ein neuer Sesquiterpenlacton-Typ aus Vernonia scorpioides (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 467-468 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Scorpiolide, A New Type of Sesquiterpene Lactone from Vernonia scorpioidesAerial parts of Vernonia scorpioides afforded in addition to the known 4α,5β-epoxy-4,5-dihydrovernonallenolide (1) the glaucolide scorpiolide (2) as well as a germacranolide with a carboxylic acid group (4). The structures were determined by high-field NMR spectroscopy. The observed Cotton effect affords the absolute configuration of 2. Accordingly, the proposed absolute configuration of the large group of glaucolides is very likely.
    Notes: Oberirdische Teile von Vernonia scorpioides liefern neben dem bereits bekannten 4α,5β-Epoxy-4,5-dihydrovernonallenolid (1) das Glaucolid Scorpiolid (2) sowie ein Germacranolid mit einer Carbonsäuregruppe (4). Die Strukturen werden durch Hochfeld-NMR-Spektroskopie geklärt. Der beobachtete Cotton-Effekt liefert die absolute Konfiguration von 2. Daher ist auch die vermutete absolute Konfiguration der großen Gruppe der Glaucolide sehr wahrscheinlich.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870356
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  • 174
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    Reactions of Sultones with Hydrazine Derivatives (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 481-482 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Propane-1,3-sultone (1) reacts with phenylhydrazine as well as with acid hydrazides yielding the corresponding sulphonic acids 2a-f in good yields. On reaction of 2,4-dimethyl-1,3-butadiene-1,4-sultone (3) with hydrazides by fusion or in a nonpolar solvent, the sultams 4a-f are obtained, and in alcohols the corresponding sulphonic acids 5a-d or the hydrazine derivative 6 are obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870359
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  • 175
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    Acylwanderung in N-geschützte Aminosäuren enthaltenden Diacylaminen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 483-484 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangement of Diacylamines Containing N-Protected Amino AcidsA new rearrangement of diacylamines containing N-protected amino acids has been discovered. The structures of two rearrangement products - N-benzoyl-N-(benzyloxycarbonyl)glycinanilide (4a) and N-benzoyl-N-[(1,1-dimethylethoxy)carbonyl]glycinanilide (4b) - were solved by X-ray analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870360
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  • 176
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    Reaktionen mit 2-Aza-1,3-butadien-Derivaten, 2. Ein einfacher Zugang zum Pyrrolo[1,2-c]pyrimidin-und Pyrrolo[3,2-c]pyridin-System (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 491-494 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions with 2-Aza-1,3-butadiene Derivatives, 2. - A Facile Access to the Pyrrolo[1,2-c]pyrimidine and Pyrrolo[3,2-c]pyridine System3-Methylindole (4) as well as pyrrole derivatives 7 react under proton catalysis with the 2-azabutadiene 2a in the α-position. The subsequent ring closure into a free neighbouring position (N or C), which is also affected by further substituents, furnishes the pyrrolo[1,2-c]pyrimidine 5 and 8, resp., and/or the pyrrolo[3,2-c]-pyridine 9.
    Notes: 3-Methylindol (4) wie auch Pyrrol-Derivate 7 reagieren unter Protonenkatalyse mit dem 2-Azabutadien-Derivat 2a in der α-Position. Der folgende Ringschluß in eine freie Nachbarposition (N oder C), der auch durch weitere Substituenten beeinflußt wird, liefert das Pyrrolo[1,2-c]pyrimidin 5 bzw. 8 und/oder das Pyrrolo[3,2-c]pyridin 9.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870362
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  • 177
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    N-Unsubstituted (Carbamoyloxy)nitrostyrenes: A New Series of Aryl-β-nitroalkenes with Fungicidal Properties (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 495-498 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N-Unsubstituierte (Carbamoyloxy)nitrostyrole: Eine neue Serie von Aryl-β-nitroalkenen mit fungiziden Eigenschaften(Chlorsulfonyl)isocyanat reagiert mit Hydroxynitrostyrolen 1 zu entsprechenden N-unsubstituierten Carbamaten 3. Letztere lassen sich mit p-Tosylchlorid zu den entsprechenden Sulfonaten 4 umestern. Analoge Phosphate erhält man durch Umsetzung von Diethylchlorphosphat mit 1. Die Verbindungen 3, 4 und 5 sind neuartige Aryl-β-nitroalkene mit pestiziden Eigenschaften. Die Verbindungen 3 reagieren mit o-Phenylendiamin zu Benzimidazolon sowie entsprechenden 2-Arylbenzimidazolen 7. Die molluskiziden und antimikrobiellen Eigenschaften der Produkte werden diskutiert.
    Notes: Chlorosulfonyl isocyanate reacts with hydroxynitrostyrenes 1 to give the corresponding N-unsubstituted carbamates 3. The latter undergo transesterification with p-toluenesulfonyl chloride to give the corresponding sulfonates 4. The analogous phosphates 5 are obtained by treating diethyl chlorophosphate with 1. Compounds 3, 4, and 5 present a novel series of aryl-β-nitroalkenes of pesticidal importance. Compounds 3 react with o-phenylenediamine to afford benzimidazolone along with the corresponding 2-arylbenzimidazoles 7. The molluscicidal and antimicrobial activities of the products are discussed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870363
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  • 178
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    Heterocyclische Siebenring-Verbindungen, XXXI. Das photochemische Verhalten monosubstituierter 1-Benzothiepine (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 505-507 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic Seven-Membered Ring Compounds, XXXI. - The Photochemical Behaviour of Monosubstituted 1-BenzothiepinesPhotoisomerization of the monosubstituted 1-benzothiepines 4 yields only the products 5 of the normal butadiene-cyclobutene cyclization 5. This result is confirmed by the photochemical behaviour of [4-D1]5-methoxy-1-benzothiepine (4c).
    Notes: Die Photoisomerisierung der monosubstituierten 1-Benzothiepine 4 ergibt nur die Produkte 5 eines normalen Butadien-Cyclobuten-Ringschlusses. Dies wird abgesichert durch das photochemische Verhalten von [4-D1]5-Methoxy-1-benzothiepin (4c).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870365
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  • 179
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    Chemie der Ginkgolide, II. Isolierung und Strukturaufklärung eines neuen Ginkgolids (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 521-526 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Ginkgolides, II. - Isolation and Structural Elucidation of a New GinkgolideFrom leaves of the Ginkgo tree a new ginkgolide (5) is isolated which we name ginkgolide J. The structural elucidation was achieved by spectroscopic methods as well as by chemical correlation to ginkgolide C.
    Notes: Aus Blättern des Ginkgo-Baumes wird ein neues Ginkgolid (5) isoliert, das wir als Ginkgolid J bezeichnen. Die Strukturaufklärung gelang sowohl mit spektroskopischen Methoden als auch durch chemischen Korrelation mit Ginkgolid C.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870368
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  • 180
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    Chemie reaktiver Kationen von Schwefeldioxidanalogen, XV. Umsetzung mit Keteniminen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 527-529 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Reactive Cations Derived from Sulfur Dioxide Analogues, XV. - Reaction with KeteniminesThe reaction of the cationic N-sulfinylamine 1 with ketenimines 2 leads to four-membered heterocycles 7 which can be hydrolyzed under basic conditions to give the corresponding amidines 8.
    Notes: N-Methyl-N-sulfinylmethanaminium-tetrafluoroborat (1) setzt sich mit Keteniminen 2 zu 1,2-Thiazetidiniumsalzen 7 um, die sich basisch zu den entsprechenden Amidinen 8 hydrolysieren lassen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870369
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  • 181
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    Heteroaromatic Acetonitriles, I. Reactions of 5-Substituted (4H-1,2,4-Triazol-3-yl)acetonitriles with Salicylaldehyde (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 541-543 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On heating of the (4H-1,2,4-triazol-3-yl)acetonitriles 2a and 2b with salicylaldehyde (1) in the presence of bases the 12H-[1]benzopyrano[3,2-e]-1,2,4-triazolo[4,3-c]pyrimidines 6a and 6b were obtained. A mechanism for these reaction is proposed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870372
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  • 182
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    Reaction of the Silver Salts of Arylnitroacetonitriles with 9-Bromofluorene Synthesis of 9-(α-Cyanoarylidene)fluorenes (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 537-540 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The silver salts 1a-d react with 9-bromofluorene to give both C- and O-alkylated products 2 and 3. The latter decompose to yield 9-fluorenone and the α-cyanooximes 5. The products 2 upon treatment with NaOH/EtOH eliminate HNO2 to afford 9-(α-cyanoarylidene)fluorenes 4 in 80% yield. 9-Chloro-9-phenylfluorene reacts with the salt 1a to give only the C-alkylated product 6 in 70% yield.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870371
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  • 183
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    Untersuchung des dynamischen Verhaltens von Zuckermodellverbindungen durch Kernresonanzspektroskopie (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 547-548 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigation of the Dynamic Behavior of Sugar Model Compounds by Nuclear Magnetic ResonanceRate constants for the tautomeric equilibrium of 5-hydroxypentanal, a model compound for aldopyranose, have been determined by line-shape analysis of the 13C-NMR spectrum obtained from an acidified solution in water.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870374
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  • 184
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    Total Synthesis of (-)-Malyngolide and of Its Three Stereomers (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 231-233 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Totalsynthese von (-)-Malyngolid und seinen drei Stereomeren(-)-Malyngolid (1a) und seine drei Stereomeren 1b-d werden aus dem Allylalkohol 4 in jeweils 10% Gesamtausbeute synthetisiert. Schlüsselstufen der Synthese sind die Sharpless-Epoxidierung des Allylalkohols 4 und die radikalische C—C-Bindungsbildung mit dem Iodid 3 und Methacrylsäure-methylester (2). Diese radikalische C—C-Bindungsbildung benötigt nur geringe Mengen an Organozinnverbindungen.
    Notes: (-)-Malyngolide (1a) and its three stereomers 1b-d are synthesized from the allylic alcohol 4 in total yields of about 10% each. The key reaction steps are Sharpless epoxidation of the allylic alcohol 4 and radical C—C bond formation with the iodide 3 and methyl methacrylate (2). This radical chain reaction needs only small amounts of organotin compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870313
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  • 185
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    Einfache Synthesen der anomeren, an C-6 modifizierten Galacto- und Glucopyranosylazide (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 235-241 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Facile Syntheses of Galacto- and Glucopyranosyl Azides Substituted at C-6Acetylated 6-chloro-, 6-bromo-, 6-iodo-, and 6-azido-6-deoxy-α-D-glucopyranosyl azides (26, 22, 17, 30), -β-D-glucopyranosyl azides (27, 23, 18, 31), -α-D-galactopyranosyl azides (29, 25, 20, 32), and -β-D-galactopyranosyl azides (29, 25, 20, 33) have been obtained by nucleophilic displacement reactions of the appropriate 6-O-(p-toluenesulfonates) 9-12. Hydrogen iodide elimimation from the 6-iodo-6-deoxyglycosyl azides 17-20 by DBU or DBN leads to the hex-5-enopyranosyl azides with α-D-xylo (43), β-D-xylo (44), α-L-arabino (46), and β-L-arabino configuration. The structures, anomeric configurations, and conformations of the products were determined by 1H-NMR spectroscopy.
    Notes: Acetylierte 6-Chlor-, 6-Brom-, 6-Iod- und 6-Azido-6-desoxy-Derivate des α-D-Glucopyranosylazids (26, 22, 17, 30) und β-D-Glucopyranosylazids (27, 23, 18, 31) sowie des α-D-Galactopyranosylazids (28, 24, 19, 32) und β-D-Galactopyranosylazids (29, 25, 20, 33) wurden durch nucleophile Substitutionsreaktionen der entsprechenden 6-O-(p-Toluolsulfonate) 9-12 gewonnen. Die Dehdroiodierung der 6-Iod-6-desoxyazide 17-20 mit DBU oder DBN führte zu den Hex-5-enopyranosylaziden mit α-D-xylo- (43) und β-D-xylo- (44), sowie α-L-arabino- (46) und β-L-arabino-Konfiguration (45). Die Strukturen, die anomeren Konfigurationen und die Konformationen der Produkte werden durch 1H-NMR-Spektroskopie bestimmt.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870314
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  • 186
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    Investigations on the Chemistry of Berbanes, XII. Synthesis of Pseudo-Depyrroloyohimbine Analogues (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 243-247 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Untersuchungen über Verbindungen mit Berban-Gerüst, XII. - Synthese von Pseudo-Depyrroloyohimbin-AnalogenDas bereits beschriebene Ketonitril 1 ergibt mit dem Phosphonsäureester 2 die drei Isomere 3, 4 und 5. Katalytische Reduktion von 4 führt zu 6 und 7a. Der Methylester 7b entsteht durch Hydrolyse von 7a und nachfolgende Veresterung. Dieckmann-Kondensation von 7b liefert die Pseudo-Berbane 9a und 9b. Die Stereochemie der neuen Verbindungen wurde mit physikalischen (NMR, IR, MS) und chemischen Methoden bewiesen.
    Notes: The known keto nitrile 1 reacts with the phosphonate 2 to give the three isomers 3, 4, and 5. Catalytic reduction of 4 affords 6 and 7a. By hydrolysis and subsequent esterification of 7a the corresponding methyl ester 7b is obtained. Dieckmann condensation of 7b leads to the pseudoberbanes 9a, 9b. The stereochemistry of the compounds was proved by physical (NMR, IR, MS) and chemical methods.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870315
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  • 187
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    Bausteine von Oligosacchariden, LXXVIII. Synthese von KDO-haltigen Lipoid-A-Analoga (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 249-258 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, LXXVIII. - Synthesis of KDO-Containing Lipid A AnaloguesThe non-neighbouring group supported glycosidation of 12 with the suitably protected glycosyl bromide 9 of 2-azido-2-deoxy-D-glucose leads - in the presence of a heterogeneous silver catalyst - to the formation of the β-(1→6)-glycosidically linked disaccharide 14. It consists of two 2-azido-2-deoxy-D-glucose units. Partial deblocking of 14 furnishes 15. On glycosidation with KDO bromide this compound yields the trisaccharide 16, which contains a KDO unit in an α-(2→6) ketosidic bond. Reduction of the two azido groups followed by amidation with (R)-3-hydroxymyristic acid and further deblocking generates the trisaccharide α-KDO-(2→6)-β-D-GlcA-(1→6)-D-GlcA 20 with two 3-hydroxy fatty acid residues in an amidic linkage.
    Notes: Die Umsetzung des Pyranosylbromids 9 der 2-Azido-2-desoxy-D-glucose mit dem Akzeptor 12 führt bei Gegenwart eines heterogenen Silberkatalysators ohne Nachbargruppenbeteiligung unter Inversion zum β-(1→6)-glycosidisch verknüpften Disaccharid 14 aus zwei 2-Azido-2-desoxy-D-glucose-Einheiten. Nach partieller Entblockierung zu 15 ist die Anknüpfung eines KDO-Restes unter Bildung einer α-(2→6)-ketosidischen Bindung zum Trisaccharid 16 möglich. Nach Reduktion der Azidogruppen und Anknüpfung von (R)-3-Hydroxymyristinsäure-Resten gelangt man nach Entblockierung zum Trisaccharid α-KDO-(2→6)-β-D-GlcA-(1→6)-D-GlcA 20, das amidartig zwei 3-Hydroxyfettsäure-Reste gebunden enthält.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870316
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  • 188
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    Synthese von Dipeptid-triestern mit Phosphonoglycin als N-terminaler Komponente (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 267-269 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Dipeptide Triesters with Phosphonoglycine as N-terminal ComponentStarting with diethyl (isocyanomethyl)phosphonate (1) and methyl α-isocyanatoalkanoates 3 a series of dipeptide triesters 5 was synthesized. As found with 5a, hydrolysis of 5 to give the dipeptides 6 with (phosphono)Gly as N-terminal component is possible, but 6 could not be obtained in pure form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870320
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  • 189
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    Bausteine von Oligosacchariden, LXXIX. Synthese der Sequenz α-KDO-(2 → 4)-α-KDO-(2 → 6)-D-GlcN der inneren Core-Struktur von Lipopolysacchariden (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 273-281 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, LXXIX1). - Synthesis of the Sequence α-KDO-(2→4)-α-KDO-(2→6)-D-GlcN of the “Inner Core” Structure of LipopolysaccharidesThe glycosyl halide of 3-deoxy-D-manno-2-octulosonic acid (KDO) (5) reacts with the D-glucosamine derivative 4 to give the α-(2→6) glycosidically linked disaccharide 6. After deacetylation from 6 to 7 and conversion into the isopropylidene sugar 16, the disaccharide can be used for a subsequent glcoside synthesis. The coupling of 5 with 16 affords regioselectively the α-(2→4) linked trisaccharide 18. In a series of deblocking steps, α-KDO-(2→4)-α-KDO-(2→6)-D-GlcN (24) can be obtained, which is an important sequence of the “inner core” structure of the lipopolysaccharides.
    Notes: Das Glycosylhalogenid der 3-Desoxy-D-manno-2-octulosonsäure (KDO) (5) läßt sich mit dem D-Glucosamin-Derivat 4 zum α-(2→6)-glycosidisch verknüpften Disaccharid 6 umsetzen. Nach Entacetylierung von 6 zu 7 und Überführung in die Isopropylidenverbindung 16 kann das Disaccharid erneut für eine Glycosidsynthese eingesetzt werden. Die Umsetzung von 5 mit 16 ergibt regioselektiv das α-(2→4)-glycosidisch verknüpfte Trisaccharid 18. Durch eine Folge von Entblockierungsschritten ist hieraus α-KDO-(2→4)-α-KDO-(2→6)-D-GlcN (24) zu erhalten, das eine wichtige Sequenz der inneren Core-Struktur von Lipopolysacchariden darstellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870322
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  • 190
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    Kaliumsuperoxid und ein neuer Weg von myo- zu scyllo-Inositderivaten (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 645-646 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Potassium Superoxide and a Novel Route from myo- to scyllo-Inositol DerivativesPotassium superoxide has been used successfully as oxygen nucleophile in order to convert a myo- into a scyllo-inositol derivative (1→3). This model reaction offers a novel and simple route to differently substituted, non-centrosymmetric derivatives of the rare scyllo-inositol starting from its commercially available myo isomer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870715
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  • 191
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    Enantiomere des konfigurationsstabilen C-Methylthalidomids (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 647-648 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomers of Configurationally Stable C-MethylthalidomideThe enantiomers of 2-(3-methyl-2,6-dioxo-3-piperidinyl)-1H-isoindole-1,3(2H)-dione (1c), the configurationally stable C-methyl derivative of thalidomide (1a), were synthesized by chromatographic resolution of rac-2-(3-methyl-2-oxo-3-piperidinyl)-1H-isoindole-1,3(2H)-dione (1b) and subsequent oxidation of the enantiomers. The enantiomeric purity of (+)- and (-)-1c was proven by capillary gas chromatography on a chiral stationary phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870716
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  • 192
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    Umsetzung bifunktioneller Moleküle mit Acceptor-substituierten Butadienen (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 655-659 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Bifunctional Molecules with Acceptor-Substituted ButadienesThe butadienyl sulfone 1 and the chlorobutenyl sulfone 2 react under six-ring annulation with salicylaldehyde to give 4 and with 1-(cyclohexenyl)piperidine to give 7. Reaction with 2-pyrrolecarbaldehyde yields the 3a-azaazulenes 10a-c together with the vinylcyclopent-indolizine 14, formed in a 6-step reaction sequence. The isomeric imidazolecarbaldehydes 15 and 17 react analogously to yield the diazaazulenes 16 and 18, respectively. From a multistep reaction of 2-pyrrolecarbaldehyde and the bisphosphonium salt 20 the pyrrolyl-3a-azaazulene 23a has been obtained.
    Notes: Das Butadienylsulfon 1 und das Chlorbutenylsulfon 2 reagieren unter Sechsring-Anellierung mit Salicylaldehyd zu 4 und mit 1-(Cyclohexenyl)piperidin zu 7. Mit 2-Pyrrolcarbaldehyd entsteht neben den erwarteten 3a-Azaazulenen 10a-c das Vinylcyclopent-indolizin 14 in einer sechsstufigen Reaktionsfolge. Die beiden Imidazolcarbaldehyde 15 und 17 reagieren analog zu den Diazaazulenen 16 und 18. Das Pyrrolyl-3a-azaazulen 23a entsteht in einer Mehrstufenreaktion aus 2-Pyrrolcarbaldehyd und dem Bisphosphoniumsalz 20.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870803
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  • 193
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    Neuartige Seco- und Nor-Beyeran-Derivate aus Myriocephalus stuartii (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 665-670 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Novel Seco- and Nor-Beyerane Derivatives from Myriocephalus stuartiiThe investigation of a representative of the Australian genus Myriocephalus (Compositae, tribe Inuleae) affords in addition to known beyerane derivatives eight new ones as well as four seco compounds and two nor-diterpenes with a new carbon skeleton. Furthermore, the known coumarins obliquin and its 5-methoxy derivative were isolated. Two nor-beyerane lactones are obtained by lead tetraacetate oxidation. The structures were elucidated by their spectroscopic data, by partial synthesis, and by some chemical transformations.
    Notes: Die Untersuchung eines Vertreters der australischen Gattung Myriocephalus (Compositae, Tribus Inuleae) liefert neben bekannten Beyeran-Derivaten acht neue sowie vier Seco-Verbindungen und zwei Nor-Diterpene mit neuem Kohlenstoffgerüst. Außerdem isoliert man die bekannten Cumarine Obliquin und dessen 5-Methoxy-Derivat. Zwei Nor-Beyeranlactone werden durch Bleitetraacetat-Oxidation erhalten. Die Strukturen werden durch ihre spektroskopischen Daten, durch Partialsynthese und einige chemische Umwandlungen geklärt.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870805
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  • 194
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    Nucleophilic Acylation of 3,4-Dihydroisoquinolinium Salts. Diastereoselective Synthesis of the Protoberberine Alkaloid (±)-Corydaline and of Analogous Compounds (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 311-319 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleophile Acylierung von 3,4-Dihydroisochinolinium-Salzen. Diastereoselektive Synthese des Protoberberinalkaloids (±)-Corydalin und analoger VerbindungenDie nucleophile Acylierung der 3,4-Dihydroisochinolinium-Salze 3 mit den lithiierten Enolethern 6, 7 und 8 bzw. Thioenolethern 14 ergibt mit meist sehr guten Ausbeuten die Addukte 4, 9 bzw. 16. Hydrolyse von 4 führt mit 94-97% Ausbeute zu den Ketonen 5, die nach Behandlung mit konz. Salzsäure und nachfolgender Reduktion mit NaH3BCN über die Enamine 18 in die Dibenzochinolizidine 19 übergeführt werden können; so ergibt 5b mit 84% Ausbeute (±)-Corydalin (2 ≡ 19b).
    Notes: Nucleophilic acylation of 3,4-dihydroisoquinolinium salts 3 with lithiated enol ethers 6, 7, and 8 or vinyl sulfides 14 leads to the adducts 4, 9, and 16, respectively, in mostly excellent yields. Hydrolysis of 4 affords 94-97% of the ketones 5, which are transformed by treatment with conc. hydrochloric acid and successive reduction with NaH3BCN via the enamines 18 into the dibenzoquinolizidines 19; thus 5b gives (±)-corydaline (2 ≡ 19b) in 84% yield.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870327
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  • 195
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    Synthesis of Aryl Azide Analogues of Insect Juvenile Hormones as Reagents for the Photoaffinity Labeling of Juvenile Hormone Binding Proteins (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 327-331 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von Arylazid-Analogen der Juvenilhormone von Insekten als Reagenzien für die Photoaffinitätsmarkierung von Juvenilhormon-bindenden Proteinen.Es werden Synthesen der Azidophenyl-6,7-epoxygeranylether rac-4c und rac-4d sowie des Azidobenzoates rac-6 beschrieben. p-Azidophenyl-6,7-epoxygeranylether (rac-4c) zeigt eine hohe Bindungsaffinität zu dem in der Wanderheuschrecke Locusta migratoria vorkommenden Juvenilhormon-Bindungsprotein. Bestrahlung bei 254 nm oder bei 300 nm führt zu rascher Photolyse. rac-4c wird als neues Reagenz zur Untersuchung von Juvenilhormon-bindenden Proteinen aus solchen Insektenspezies, deren natürliches Hormon 1a ist, vorgeschlagen. Weiterhin werden Synthesen und Bindungseigenschaften des Arylketons rac-4e und des Vinylketons rac-7 beschrieben.
    Notes: The azidophenyl 6,7-epoxygeranyl ethers rac-4c and rac-4d and the azidobenzoate rac-6 were synthesized. p-Azidophenyl 6,7-epoxygeranyl ether (rac-4c) shows a high affinity to the juvenile hormone binding protein of the migratory locust, Locusta migratoria. Fast photolysis is observed upon irradiation at 254 nm and at 300 nm. It is proposed that rac-4c is useful as a new reagent for the study of juvenile hormone binding proteins of insects in which the natural hormone is 1a. The synthesis and binding properties of the aryl ketone rac-4e and the vinyl ketone rac-7 are described also.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870329
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  • 196
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    Synthese von Americanin-D (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 357-360 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Americanin-DBy regioselective self-coupling with silver oxide as oxidant the 2,3-trans-2-phenylbenzofuran 8 was synthesized in good yield. Reduction of 8 led in an unambiguous way to americanin-D (rac-1). Synthetic and natural product were identical in every respect.
    Notes: Durch eine regioselektiv verlaufende Selbstkupplung von Kaffeesäure-ethylester (6) mit Silberoxid als Oxidationsmittel wurde in guter Ausbeute das 2,3-Trans-2-Phenylbenzofuranderivat 8 und durch dessen Reduktion Americanin-D (rac-1) auf eindeutigem Wege synthetisiert. Syntheseprodukt und Naturstoff waren in jeder Hinsicht miteinander identisch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870334
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  • 197
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    Chemie und Stereochemie der Iridoide, IX. EPC-Synthese von (1R,2R,2″Z)-(-)-Methyl-jasmonat aus Catalpol - Kristall- und Molekularstruktur von Methyl-dehydrojasmonat-semicarbazon (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 361-366 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry and Stereochemistry of Iridoids, IX1). - EPC Synthesis of (1R,2R,2″Z)-(-)-Methyl Jasmonate from Catalpol - Crystal and Molecular Structure of Methyl Dehydrojasmonate SemicarbazoneCatalpol is converted into the enantiomerically pure (1R,2R,2″Z)-(-)-methyl jasmonate (1) by a 16-step synthesis (yield about 7%). The R-configuration at C-1 of 1 results from the synthesis. The complete stereochemistry of 1 is confirmed by the X-ray analysis of methyl dehydrojasmonate semicarbazone (semicarbazone of 12).
    Notes: In einer 16stufigen Synthese wird aus Catalpol das enantiomerenreine (1R,2R,2″Z)-(-)-Methyl-jasmonat (1) hergestellt (Ausbeute ca. 7%). Durch die Synthese ist die R-Konfiguration an C-1 von 1 vorgegeben. Mit der Röntgenstrukturanalyse des Methyl-dehydrojasmonat-semicarbazons (Semicarbazon von 12) wird die vollständige Stereochemie von 1 bestätigt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870335
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  • 198
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    Syntheses and Structures of 2-(O-Acylhydroxyimino)-1,3-indandiones (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 375-376 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-(O-Acetylhydroxyimino)-1,3-indandione (1) and 2-[O-(N-tert-Butyloxycarbonylglycyl)hydroxyimino]-1,3-indandione (2) have been synthesized by the mixed anhydrides method. The infrared and the 13C-NMR spectra, as well as the quantum chemical calculations show that this kind of active esters has the structure I.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870337
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  • 199
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    Neue Ergebnisse zur Stereoselektivität der Ketoketen-Dimerisierung (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 377-379 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Results on the Stereoselectivity of Ketoketene DimerizationsAlkylation of 2,4-disubstituted 1,3-cyclobutanediones results in tetraalkylcyclobutanediones with trans-positioned large residues. Thermal dimerization of isopropylmethylketene gives cis-dimer 4a as major product, whereas methylneopentylketene yields more of the trans-isomer 5b. The results are discussed in connection with a [π2s + π2a] process.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870338
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  • 200
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    Chirale Isoprenylether aus 3-Ethoxy-2-methylacrolein durch vinyloge Umesterung und Wittig-Alkenylierung (1987)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 385-386 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral Isoprenyl Ethers from 3-Ethoxy-2-methylacrolein by Vinylogous Transesterification and Wittig AlkenylationChiral isoprenyl ethers 5 as potential starting materials for enantioselective syntheses of cyclic terpenes are shown in a model reaction to be prepared by vinylogous transesterification of 3-ethoxy-2-methylacrolein (1) with chiral alcohols such as (R)- and (S)-1,2-O-isopropylideneglycerol 2 and subsequent Wittig alkenylation of the resulting chiral 3-alkoxy-2-methylacroleins 3.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198719870340
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